diff --git a/lib/rules/template-no-redundant-role.js b/lib/rules/template-no-redundant-role.js
index abaf75cf2d..604274b545 100644
--- a/lib/rules/template-no-redundant-role.js
+++ b/lib/rules/template-no-redundant-role.js
@@ -1,3 +1,5 @@
+const { roles } = require('aria-query');
+
 const DEFAULT_CONFIG = {
   checkAllHTMLElements: true,
 };
@@ -37,6 +39,48 @@ const ALLOWED_ELEMENT_ROLES = [
   { name: 'input', role: 'combobox' },
 ];
 
+// Per HTML-AAM, <select> maps to "combobox" only when neither `multiple` nor
+// `size > 1` is set; otherwise it maps to "listbox". Mirrors jsx-a11y's
+// src/util/implicitRoles/select.js.
+//
+// Returns 'combobox' / 'listbox' for static cases, or 'unknown' when a
+// dynamic `multiple` or `size` value blocks a decision. Callers should skip
+// flagging on 'unknown' to avoid false positives.
+function getSelectImplicitRole(node) {
+  const attrs = node.attributes || [];
+  const multipleAttr = attrs.find((a) => a.name === 'multiple');
+  if (multipleAttr) {
+    // Valueless `multiple` or static string value — statically present.
+    if (!multipleAttr.value || multipleAttr.value.type === 'GlimmerTextNode') {
+      return 'listbox';
+    }
+    // Dynamic `multiple={{...}}` — Ember omits bound boolean attributes at
+    // runtime when the value is falsy, so we can't tell statically whether
+    // the implicit role is combobox or listbox.
+    return 'unknown';
+  }
+  const sizeAttr = attrs.find((a) => a.name === 'size');
+  if (sizeAttr) {
+    // Valueless `size` (e.g. `<select size>`) — per HTML boolean-attr
+    // semantics the attribute value is an empty string, which Number()
+    // parses as 0. Per HTML's default size (>1 → listbox), 0 leaves the
+    // implicit role as combobox. Treat the same as the static-0 case.
+    if (!sizeAttr.value) {
+      return 'combobox';
+    }
+    if (sizeAttr.value.type !== 'GlimmerTextNode') {
+      // Dynamic `size={{...}}` / concat — can't tell whether the runtime
+      // value is >1 or not, so bail out instead of risking a false positive.
+      return 'unknown';
+    }
+    const sizeValue = Number(sizeAttr.value.chars);
+    if (Number.isFinite(sizeValue) && sizeValue > 1) {
+      return 'listbox';
+    }
+  }
+  return 'combobox';
+}
+
 // Mapping of roles to their corresponding HTML elements
 // From https://www.w3.org/TR/html-aria/
 const ROLE_TO_ELEMENTS = {
@@ -45,6 +89,10 @@ const ROLE_TO_ELEMENTS = {
   button: ['button'],
   cell: ['td'],
   checkbox: ['input'],
+  // <select> is a combobox by default per HTML-AAM (section 4). When
+  // `multiple` is present or `size > 1`, it maps to "listbox" instead;
+  // that case is handled at the call site via getSelectImplicitRole.
+  combobox: ['select'],
   columnheader: ['th'],
   complementary: ['aside'],
   contentinfo: ['footer'],
@@ -125,7 +173,19 @@ module.exports = {
 
         let roleValue;
         if (roleAttr.value && roleAttr.value.type === 'GlimmerTextNode') {
-          roleValue = roleAttr.value.chars || '';
+          // ARIA role tokens are compared ASCII-case-insensitively, and the
+          // attribute is a space-separated fallback list. Per WAI-ARIA §4.1,
+          // UAs walk tokens for the first role they RECOGNISE — unknown
+          // leading tokens are skipped, subsequent tokens are author-provided
+          // fallbacks. `role="xxyxyz button"` resolves to `button`;
+          // `role="tab button"` resolves to `tab` (recognised first, even
+          // though no implicit mapping — this rule then has nothing to flag).
+          const tokens = (roleAttr.value.chars || '').trim().toLowerCase().split(/\s+/u);
+          const firstRecognised = tokens.find((t) => t && roles.has(t));
+          if (!firstRecognised) {
+            return;
+          }
+          roleValue = firstRecognised;
         } else {
           // Skip dynamic role values
           return;
@@ -138,9 +198,25 @@ module.exports = {
 
         const elementsWithRole = ROLE_TO_ELEMENTS[roleValue];
         if (!elementsWithRole) {
+          // Role is recognised by ARIA but has no implicit-element mapping
+          // in this table — nothing can be redundant.
           return;
         }
 
+        // <select>'s implicit role depends on attributes (HTML-AAM):
+        //   - default (no `multiple`, `size` absent or <= 1) → "combobox"
+        //   - `multiple` or `size` > 1                        → "listbox"
+        // A role attribute is only redundant when it matches the element's
+        // computed implicit role. Guard both combobox and listbox against
+        // the opposite configuration, and bail when `size` is dynamic
+        // ('unknown') rather than risk a false positive.
+        if (node.tag === 'select' && (roleValue === 'combobox' || roleValue === 'listbox')) {
+          const implicit = getSelectImplicitRole(node);
+          if (implicit !== roleValue) {
+            return;
+          }
+        }
+
         const isRedundant =
           elementsWithRole.includes(node.tag) &&
           !ALLOWED_ELEMENT_ROLES.some((e) => e.name === node.tag && e.role === roleValue);
diff --git a/tests/lib/rules/template-no-redundant-role.js b/tests/lib/rules/template-no-redundant-role.js
index 4d529b2fe1..b3e5b983f6 100644
--- a/tests/lib/rules/template-no-redundant-role.js
+++ b/tests/lib/rules/template-no-redundant-role.js
@@ -48,6 +48,24 @@ ruleTester.run('template-no-redundant-role', rule, {
       options: [{ checkAllHTMLElements: false }],
     },
     '<template><input role="combobox"></template>',
+    // <select multiple> has implicit role listbox, so combobox is not redundant.
+    '<template><select role="combobox" multiple></select></template>',
+    // <select size="5"> (size > 1) has implicit role listbox.
+    '<template><select role="combobox" size="5"></select></template>',
+    // Default <select> (no `multiple`, `size` absent or <= 1) has implicit
+    // role "combobox" — an explicit `role="listbox"` overrides to listbox
+    // and is NOT redundant.
+    '<template><select role="listbox"></select></template>',
+    '<template><select role="listbox" size="1"></select></template>',
+    // Dynamic `multiple={{...}}` — can't determine implicit role statically,
+    // so neither `role="combobox"` nor `role="listbox"` is flagged.
+    '<template><select role="combobox" multiple={{this.isMulti}}></select></template>',
+    '<template><select role="listbox" multiple={{this.isMulti}}></select></template>',
+
+    // Role-fallback: first recognised token wins. `role="tab button"` on
+    // <button> resolves to `tab` (non-redundant — button's implicit is
+    // `button`, not `tab`). WAI-ARIA §4.1 fallback-list semantics.
+    '<template><button role="tab button"></button></template>',
   ],
   invalid: [
     {
@@ -69,6 +87,45 @@ ruleTester.run('template-no-redundant-role', rule, {
         },
       ],
     },
+    // Non-landmark same-role redundancy — covered by jsx-a11y / vue-a11y too.
+    {
+      code: '<template><button role="button"></button></template>',
+      output: '<template><button></button></template>',
+      errors: [{ message: 'Use of redundant or invalid role: button on <button> detected.' }],
+    },
+    {
+      code: '<template><img role="img" /></template>',
+      output: '<template><img /></template>',
+      errors: [{ message: 'Use of redundant or invalid role: img on <img> detected.' }],
+    },
+    {
+      // Valueless `<select size>` — per HTML boolean-attr semantics, the
+      // attribute value is an empty string; Number('') is 0; 0 is NOT > 1,
+      // so the implicit role stays combobox. `role="combobox"` is therefore
+      // redundant and must be flagged.
+      code: '<template><select role="combobox" size></select></template>',
+      output: '<template><select size></select></template>',
+      errors: [
+        {
+          message: 'Use of redundant or invalid role: combobox on <select> detected.',
+        },
+      ],
+    },
+    {
+      // Role-fallback: unknown leading token is skipped per ARIA §4.1.
+      // `role="xxyxyz button"` resolves to `button`, which IS redundant on
+      // <button>. Autofix drops the whole role attribute — the implicit
+      // `button` role is preserved natively, so runtime semantics are
+      // unchanged. Authors who wanted the `xxyxyz` fallback for some
+      // reason can opt out via eslint-disable.
+      code: '<template><button role="xxyxyz button"></button></template>',
+      output: '<template><button></button></template>',
+      errors: [
+        {
+          message: 'Use of redundant or invalid role: button on <button> detected.',
+        },
+      ],
+    },
     {
       code: '<template><main role="main"></main></template>',
       output: '<template><main></main></template>',
@@ -155,6 +212,17 @@ hbsRuleTester.run('template-no-redundant-role', rule, {
       options: [{ checkAllHTMLElements: false }],
     },
     '<ul class="list" role="combobox"></ul>',
+    // <select> with `multiple` has implicit role "listbox", so role="combobox"
+    // is not redundant (it disagrees with the implicit role, but that is for
+    // other rules to catch — this rule only flags redundancy).
+    '<select role="combobox" multiple></select>',
+    // <select size="5"> (size > 1) has implicit role "listbox", same reasoning.
+    '<select role="combobox" size="5"></select>',
+    // Default <select> (no `multiple`, `size` absent or <= 1) has implicit
+    // role "combobox" — explicit role="listbox" overrides to listbox and is
+    // NOT redundant.
+    '<select role="listbox"></select>',
+    '<select role="listbox" size="1"></select>',
   ],
   invalid: [
     {
@@ -243,6 +311,30 @@ hbsRuleTester.run('template-no-redundant-role', rule, {
         '<select name="color" id="color" multiple><option value="default-color">black</option></select>',
       errors: [{ message: 'Use of redundant or invalid role: listbox on <select> detected.' }],
     },
+    {
+      // <select> without `multiple` or `size` defaults to role "combobox".
+      code: '<select role="combobox"></select>',
+      output: '<select></select>',
+      errors: [{ message: 'Use of redundant or invalid role: combobox on <select> detected.' }],
+    },
+    {
+      // size="1" still defaults to combobox (only size > 1 flips to listbox).
+      code: '<select role="combobox" size="1"></select>',
+      output: '<select size="1"></select>',
+      errors: [{ message: 'Use of redundant or invalid role: combobox on <select> detected.' }],
+    },
+    {
+      // Case-insensitive match on <select>, combined with the implicit-role check.
+      code: '<select role="COMBOBOX"></select>',
+      output: '<select></select>',
+      errors: [{ message: 'Use of redundant or invalid role: combobox on <select> detected.' }],
+    },
+    {
+      // Case-insensitive matching — ARIA role tokens compare as ASCII-case-insensitive.
+      code: '<body role="DOCUMENT"></body>',
+      output: '<body></body>',
+      errors: [{ message: 'Use of redundant or invalid role: document on <body> detected.' }],
+    },
     {
       code: '<main role="main"></main>',
       output: '<main></main>',