diff --git a/src/Finder.cpp b/src/Finder.cpp
index fe5d3e0b3..64b8664b3 100644
--- a/src/Finder.cpp
+++ b/src/Finder.cpp
@@ -46,6 +46,17 @@ void Finder::setSearchText(const QString &text)
     this->text = text;
 }
 
+void Finder::setSelectionRange(Sci_CharacterRange range)
+{
+    use_selection_range = true;
+    selection_range = range;
+}
+
+void Finder::clearSelectionRange()
+{
+    use_selection_range = false;
+}
+
 Sci_CharacterRange Finder::findNext(int startPos)
 {
     did_latest_search_wrap = false;
@@ -53,9 +64,34 @@ Sci_CharacterRange Finder::findNext(int startPos)
     if (text.isEmpty())
         return {INVALID_POSITION, INVALID_POSITION};
 
-    const int pos = startPos == INVALID_POSITION ? editor->selectionEnd() : startPos;
     const QByteArray textData = text.toUtf8();
 
+    if (use_selection_range) {
+        // Clamp start position to within the selection
+        const int rangeEnd = selection_range.cpMax;
+        int pos = startPos == INVALID_POSITION ? editor->selectionEnd() : startPos;
+        if (pos < selection_range.cpMin) pos = selection_range.cpMin;
+        if (pos > rangeEnd) pos = rangeEnd;
+
+        editor->setTargetRange(pos, rangeEnd);
+        editor->setSearchFlags(search_flags);
+
+        if (editor->searchInTarget(textData.length(), textData.constData()) != INVALID_POSITION) {
+            return {static_cast<Sci_PositionCR>(editor->targetStart()), static_cast<Sci_PositionCR>(editor->targetEnd())};
+        }
+        // Wrap within selection
+        if (wrap && pos > selection_range.cpMin) {
+            editor->setTargetRange(selection_range.cpMin, pos);
+            if (editor->searchInTarget(textData.length(), textData.constData()) != INVALID_POSITION) {
+                did_latest_search_wrap = true;
+                return {static_cast<Sci_PositionCR>(editor->targetStart()), static_cast<Sci_PositionCR>(editor->targetEnd())};
+            }
+        }
+        return {INVALID_POSITION, INVALID_POSITION};
+    }
+
+    const int pos = startPos == INVALID_POSITION ? editor->selectionEnd() : startPos;
+
     editor->setTargetRange(pos, editor->length());
     editor->setSearchFlags(search_flags);
 
@@ -81,9 +117,32 @@ Sci_CharacterRange Finder::findPrev()
     if (text.isEmpty())
         return {INVALID_POSITION, INVALID_POSITION};
 
-    const int pos = editor->selectionStart();
     const QByteArray textData = text.toUtf8();
 
+    if (use_selection_range) {
+        int pos = editor->selectionStart();
+        if (pos > selection_range.cpMax) pos = selection_range.cpMax;
+        if (pos < selection_range.cpMin) pos = selection_range.cpMin;
+
+        editor->setSearchFlags(search_flags);
+        auto range = editor->findText(search_flags, textData.constData(), pos, selection_range.cpMin);
+
+        if (range.first != INVALID_POSITION) {
+            return {static_cast<Sci_PositionCR>(range.first), static_cast<Sci_PositionCR>(range.second)};
+        }
+        // Wrap within selection
+        if (wrap && pos < selection_range.cpMax) {
+            range = editor->findText(search_flags, textData.constData(), selection_range.cpMax, pos);
+            if (range.first != INVALID_POSITION) {
+                did_latest_search_wrap = true;
+                return {static_cast<Sci_PositionCR>(range.first), static_cast<Sci_PositionCR>(range.second)};
+            }
+        }
+        return {INVALID_POSITION, INVALID_POSITION};
+    }
+
+    const int pos = editor->selectionStart();
+
     editor->setTargetRange(pos, editor->length());
     editor->setSearchFlags(search_flags);
 
@@ -104,17 +163,21 @@ Sci_CharacterRange Finder::findPrev()
     return {INVALID_POSITION, INVALID_POSITION};
 }
 
-// Count all occurrences in the document
+// Count all occurrences in the document (or selection if set)
 int Finder::count()
 {
     int total = 0;
 
     if (text.length() > 0) {
-        forEachMatch([&](int start, int end) {
+        auto counter = [&](int start, int end) {
             Q_UNUSED(start);
             total++;
             return end;
-        });
+        };
+        if (use_selection_range)
+            forEachMatchInRange(counter, selection_range);
+        else
+            forEachMatch(counter);
     }
 
     return total;
@@ -123,22 +186,33 @@ int Finder::count()
 Sci_CharacterRange Finder::replaceSelectionIfMatch(const QString &replaceText)
 {
     const QByteArray textData = text.toUtf8();
-    bool isRegex = editor->searchFlags() & SCFIND_REGEXP;
+    const bool isRegex = search_flags & SCFIND_REGEXP;
+    const Sci_PositionCR selectionStart = editor->selectionStart();
+    const Sci_PositionCR selectionEnd = editor->selectionEnd();
+
+    if (use_selection_range && (selectionStart < selection_range.cpMin || selectionEnd > selection_range.cpMax))
+        return {INVALID_POSITION, INVALID_POSITION};
 
     // Search just in the selection to see if the current selection is a match
-    editor->setTargetStart(editor->selectionStart());
-    editor->setTargetEnd(editor->selectionEnd());
+    editor->setTargetStart(selectionStart);
+    editor->setTargetEnd(selectionEnd);
     editor->setSearchFlags(search_flags);
 
     if (editor->searchInTarget(textData.length(), textData.constData()) != INVALID_POSITION) {
         const QByteArray replaceData = replaceText.toUtf8();
+        const Sci_PositionCR matchStart = editor->targetStart();
+        const Sci_PositionCR matchEnd = editor->targetEnd();
+        int replaceLength;
 
         if (isRegex)
-            editor->replaceTargetRE(replaceData.length(), replaceData.constData());
+            replaceLength = editor->replaceTargetRE(replaceData.length(), replaceData.constData());
         else
-            editor->replaceTarget(replaceData.length(), replaceData.constData());
+            replaceLength = editor->replaceTarget(replaceData.length(), replaceData.constData());
 
-        return {static_cast<Sci_PositionCR>(editor->targetStart()), static_cast<Sci_PositionCR>(editor->targetEnd())};
+        if (use_selection_range)
+            selection_range.cpMax += replaceLength - (matchEnd - matchStart);
+
+        return {matchStart, static_cast<Sci_PositionCR>(matchStart + replaceLength)};
     }
 
     return {INVALID_POSITION, INVALID_POSITION};
@@ -152,7 +226,9 @@ int Finder::replaceAll(const QString &replaceText)
     const QByteArray &replaceData = replaceText.toUtf8();
     const QByteArray &b = text.toUtf8();
     const char *c = b.constData();
-    Sci_TextToFind ttf {{0, (Sci_PositionCR)editor->length()}, c, {-1, -1}};
+    const Sci_PositionCR rangeStart = use_selection_range ? selection_range.cpMin : 0;
+    Sci_PositionCR rangeEnd         = use_selection_range ? selection_range.cpMax : (Sci_PositionCR)editor->length();
+    Sci_TextToFind ttf {{rangeStart, rangeEnd}, c, {-1, -1}};
     const bool isRegex = search_flags & SCFIND_REGEXP;
     int total = 0;
 
@@ -173,11 +249,22 @@ int Finder::replaceAll(const QString &replaceText)
         else
             ttf.chrg.cpMin = start + editor->replaceTarget(replaceData.length(), replaceData.constData());
 
-        // The replace could have changed the document size, so update the end of the search range
-        ttf.chrg.cpMax = editor->length();
+        // Update the end of the search range based on the length delta of this replacement.
+        // When confined to a selection, track the selection boundary precisely; otherwise
+        // expand to the full (possibly grown) document length.
+        if (use_selection_range) {
+            rangeEnd += ttf.chrg.cpMin - end;  // delta = newLength - oldMatchLength
+            ttf.chrg.cpMax = rangeEnd;
+        } else {
+            ttf.chrg.cpMax = editor->length();
+        }
 
         total++;
     }
 
+    // Keep the stored selection range in sync with the post-replacement boundary
+    if (use_selection_range)
+        selection_range.cpMax = rangeEnd;
+
     return total;
 }
diff --git a/src/Finder.h b/src/Finder.h
index 4f091eb0c..b14b1f9dd 100644
--- a/src/Finder.h
+++ b/src/Finder.h
@@ -41,6 +41,10 @@ class Finder
     Sci_CharacterRange replaceSelectionIfMatch(const QString &replaceText);
     int replaceAll(const QString &replaceText);
 
+    void setSelectionRange(Sci_CharacterRange range);
+    void clearSelectionRange();
+    bool hasSelectionRange() const { return use_selection_range; }
+
     template<typename Func>
     void forEachMatch(Func callback) { forEachMatchInRange(callback, {0, (Sci_PositionCR)editor->length()}); }
 
@@ -54,6 +58,9 @@ class Finder
     bool wrap = false;
     int search_flags = 0;
     QString text;
+
+    bool use_selection_range = false;
+    Sci_CharacterRange selection_range = {0, 0};
 };
 
 
diff --git a/src/dialogs/FindReplaceDialog.cpp b/src/dialogs/FindReplaceDialog.cpp
index dc95b0da8..7bd6b4bcb 100644
--- a/src/dialogs/FindReplaceDialog.cpp
+++ b/src/dialogs/FindReplaceDialog.cpp
@@ -82,6 +82,16 @@ FindReplaceDialog::FindReplaceDialog(ISearchResultsHandler *searchResults, MainW
     connect(this, &FindReplaceDialog::windowActivated, [=]() {
         ui->comboFind->setFocus();
         ui->comboFind->lineEdit()->selectAll();
+        updateInSelectionCheckbox();
+    });
+
+    // "In selection" checkbox: capture selection bounds when checked
+    ui->checkBoxInSelection->setEnabled(false);
+    connect(ui->checkBoxInSelection, &QCheckBox::toggled, this, [=](bool checked) {
+        if (checked) {
+            capturedSelectionRange = {static_cast<Sci_PositionCR>(editor->selectionStart()),
+                                      static_cast<Sci_PositionCR>(editor->selectionEnd())};
+        }
     });
 
     connect(this, &QDialog::rejected, [=]() {
@@ -195,6 +205,8 @@ void FindReplaceDialog::showEvent(QShowEvent *event)
 
     isFirstTime = false;
 
+    updateInSelectionCheckbox();
+
     QDialog::showEvent(event);
 }
 
@@ -267,7 +279,8 @@ void FindReplaceDialog::findAllInCurrentDocument()
     QString text = findString();
 
     finder->setSearchText(text);
-    finder->forEachMatch([&](int start, int end){
+
+    auto matchHandler = [&](int start, int end){
         // Only add the file entry if there was a valid search result
         if (firstMatch) {
             searchResultsHandler->newFileEntry(editor);
@@ -284,7 +297,12 @@ void FindReplaceDialog::findAllInCurrentDocument()
         searchResultsHandler->newResultsEntry(lineText, line, startPositionFromBeginning, endPositionFromBeginning);
 
         return end;
-    });
+    };
+
+    if (finder->hasSelectionRange())
+        finder->forEachMatchInRange(matchHandler, capturedSelectionRange);
+    else
+        finder->forEachMatch(matchHandler);
 }
 
 void FindReplaceDialog::findAllInDocuments()
@@ -314,9 +332,15 @@ void FindReplaceDialog::replace()
         convertToExtended(replaceText);
     }
 
+    const bool inSelection = ui->checkBoxInSelection->isChecked() && ui->checkBoxInSelection->isEnabled();
+    const int originalDocLength = inSelection ? editor->length() : 0;
+
     Sci_CharacterRange range = finder->replaceSelectionIfMatch(replaceText);
 
     if (ScintillaNext::isRangeValid(range)) {
+        if (inSelection)
+            capturedSelectionRange.cpMax += editor->length() - originalDocLength;
+
         showMessage(tr("1 occurrence was replaced"), "blue");
     }
 
@@ -344,8 +368,24 @@ void FindReplaceDialog::replaceAll()
         convertToExtended(replaceText);
     }
 
+    const bool inSelection = ui->checkBoxInSelection->isChecked() && ui->checkBoxInSelection->isEnabled();
+    const int originalDocLength = inSelection ? editor->length() : 0;
+
     int count = finder->replaceAll(replaceText);
     showMessage(tr("Replaced %Ln matches", "", count), "green");
+
+    // After replacing in selection, re-apply a selection covering the modified region
+    if (inSelection) {
+        const int lengthDelta = editor->length() - originalDocLength;
+        const int newEnd = capturedSelectionRange.cpMax + lengthDelta;
+        editor->setSelection(newEnd, capturedSelectionRange.cpMin);
+        capturedSelectionRange.cpMax = newEnd;
+        // If the selection collapsed (all text deleted), uncheck
+        if (newEnd == capturedSelectionRange.cpMin) {
+            ui->checkBoxInSelection->setChecked(false);
+            updateInSelectionCheckbox();
+        }
+    }
 }
 
 void FindReplaceDialog::count()
@@ -364,6 +404,12 @@ void FindReplaceDialog::setEditor(ScintillaNext *editor)
     this->editor = editor;
 
     finder->setEditor(editor);
+
+    // Reset the in-selection state when the editor changes
+    capturedSelectionRange = {0, 0};
+    ui->checkBoxInSelection->setChecked(false);
+    ui->checkBoxInSelection->setEnabled(false);
+    finder->clearSelectionRange();
 }
 
 void FindReplaceDialog::performNextSearch()
@@ -553,6 +599,12 @@ void FindReplaceDialog::prepareToPerformSearch(bool replace)
     finder->setWrap(ui->checkBoxWrapAround->isChecked());
     finder->setSearchFlags(computeSearchFlags());
     finder->setSearchText(findText);
+
+    if (ui->checkBoxInSelection->isChecked() && ui->checkBoxInSelection->isEnabled()) {
+        finder->setSelectionRange(capturedSelectionRange);
+    } else {
+        finder->clearSelectionRange();
+    }
 }
 
 void FindReplaceDialog::loadSettings()
@@ -666,6 +718,33 @@ void FindReplaceDialog::restorePosition()
     }
 }
 
+void FindReplaceDialog::updateInSelectionCheckbox()
+{
+    if (!editor) {
+        ui->checkBoxInSelection->setEnabled(false);
+        return;
+    }
+
+    const int selStart = editor->selectionStart();
+    const int selEnd   = editor->selectionEnd();
+    const bool hasSelection    = (selStart != selEnd);
+    const bool isRectangular   = editor->selectionIsRectangle();
+    const bool isMultiple      = (editor->selections() > 1);
+
+    if (hasSelection && !isRectangular && !isMultiple) {
+        ui->checkBoxInSelection->setEnabled(true);
+        // Capture the current selection bounds (only update if not already checked)
+        if (!ui->checkBoxInSelection->isChecked()) {
+            capturedSelectionRange = {static_cast<Sci_PositionCR>(selStart),
+                                      static_cast<Sci_PositionCR>(selEnd)};
+        }
+    } else {
+        ui->checkBoxInSelection->setChecked(false);
+        ui->checkBoxInSelection->setEnabled(false);
+        finder->clearSelectionRange();
+    }
+}
+
 int FindReplaceDialog::computeSearchFlags()
 {
     int flags = 0;
@@ -719,8 +798,14 @@ void FindReplaceDialog::markAll()
 
     editor->setIndicatorCurrent(markIndicator);
 
+    const bool inSelection = finder->hasSelectionRange();
+
     if (ui->checkBoxPurgeForEachSearch->isChecked()) {
-        editor->indicatorClearRange(0, editor->length());
+        if (inSelection)
+            editor->indicatorClearRange(capturedSelectionRange.cpMin,
+                                        capturedSelectionRange.cpMax - capturedSelectionRange.cpMin);
+        else
+            editor->indicatorClearRange(0, editor->length());
         clearAllBookmarks();
     }
 
@@ -730,7 +815,7 @@ void FindReplaceDialog::markAll()
     }
 
     int count = 0;
-    finder->forEachMatch([&](int start, int end) {
+    auto callback = [&](int start, int end) {
         editor->indicatorFillRange(start, end - start);
         count++;
 
@@ -742,9 +827,15 @@ void FindReplaceDialog::markAll()
         }
 
         return end;
-    });
+    };
 
-    showMessage(tr("Mark: %Ln match in entire file", "", count), "green");
+    if (inSelection) {
+        finder->forEachMatchInRange(callback, capturedSelectionRange);
+        showMessage(tr("Mark: %Ln match in selection", "", count), "green");
+    } else {
+        finder->forEachMatch(callback);
+        showMessage(tr("Mark: %Ln match in entire file", "", count), "green");
+    }
 }
 
 void FindReplaceDialog::clearAllMarks()
diff --git a/src/dialogs/FindReplaceDialog.h b/src/dialogs/FindReplaceDialog.h
index fe9fc6811..3c2431a8b 100644
--- a/src/dialogs/FindReplaceDialog.h
+++ b/src/dialogs/FindReplaceDialog.h
@@ -109,6 +109,8 @@ private slots:
     void updateFindList(const QString &text);
     void updateReplaceList(const QString &text);
 
+    void updateInSelectionCheckbox();
+
     bool isFirstTime = true;
     QPoint lastClosedPosition;
     Ui::FindReplaceDialog *ui;
@@ -118,6 +120,8 @@ private slots:
     QTabBar *tabBar;
     ISearchResultsHandler *searchResultsHandler;
     Finder *finder;
+
+    Sci_CharacterRange capturedSelectionRange = {0, 0};
 };
 
 #endif // FINDREPLACEDIALOG_H
diff --git a/src/dialogs/FindReplaceDialog.ui b/src/dialogs/FindReplaceDialog.ui
index b585c2d43..66e4bdd95 100644
--- a/src/dialogs/FindReplaceDialog.ui
+++ b/src/dialogs/FindReplaceDialog.ui
@@ -511,6 +511,13 @@
            </property>
           </widget>
          </item>
+         <item>
+          <widget class="QCheckBox" name="checkBoxInSelection">
+           <property name="text">
+            <string>In &amp;selection</string>
+           </property>
+          </widget>
+         </item>
         </layout>
        </item>
       </layout>
@@ -526,6 +533,8 @@
   <tabstop>radioExtendedSearch</tabstop>
   <tabstop>radioRegexSearch</tabstop>
   <tabstop>checkBoxRegexMatchesNewline</tabstop>
+  <tabstop>checkBoxWrapAround</tabstop>
+  <tabstop>checkBoxInSelection</tabstop>
   <tabstop>buttonFind</tabstop>
   <tabstop>buttonCount</tabstop>
   <tabstop>buttonReplace</tabstop>