diff --git a/internal/container/start.go b/internal/container/start.go
index bcda826..9defa11 100644
--- a/internal/container/start.go
+++ b/internal/container/start.go
@@ -96,6 +96,8 @@ func Start(ctx context.Context, rt runtime.Runtime, sink output.Sink, opts Start
 
 	tel := opts.Telemetry
 
+	hostEnv := filterHostEnv(os.Environ())
+
 	containers := make([]runtime.ContainerConfig, len(opts.Containers))
 	for i, c := range opts.Containers {
 		image, err := c.Image()
@@ -128,6 +130,8 @@ func Start(ctx context.Context, rt runtime.Runtime, sink output.Sink, opts Start
 			"MAIN_CONTAINER_NAME="+containerName,
 		)
 
+		env = append(env, hostEnv...)
+
 		var binds []runtime.BindMount
 		if socketPath := rt.SocketPath(); socketPath != "" {
 			binds = append(binds, runtime.BindMount{HostPath: socketPath, ContainerPath: "/var/run/docker.sock"})
@@ -445,6 +449,20 @@ func awaitStartup(ctx context.Context, rt runtime.Runtime, sink output.Sink, con
 	}
 }
 
+// filterHostEnv returns the subset of host environment entries that should be
+// forwarded to the emulator container. It keeps CI and LOCALSTACK_* variables
+// but explicitly drops LOCALSTACK_AUTH_TOKEN so the host value cannot overwrite
+// the token resolved by lstk (which may come from the keyring).
+func filterHostEnv(envList []string) []string {
+	var out []string
+	for _, e := range envList {
+		if strings.HasPrefix(e, "CI=") || (strings.HasPrefix(e, "LOCALSTACK_") && !strings.HasPrefix(e, "LOCALSTACK_AUTH_TOKEN=")) {
+			out = append(out, e)
+		}
+	}
+	return out
+}
+
 func hasDuplicateContainerTypes(containers []config.ContainerConfig) bool {
 	seen := make(map[config.EmulatorType]bool)
 	for _, c := range containers {
diff --git a/internal/container/start_test.go b/internal/container/start_test.go
index 518157e..c75d4ce 100644
--- a/internal/container/start_test.go
+++ b/internal/container/start_test.go
@@ -53,14 +53,26 @@ func TestEmitPostStartPointers_WithoutWebApp(t *testing.T) {
 	assert.Contains(t, got, "> Tip:")
 }
 
-func TestServicePortRange_ReturnsExpectedPorts(t *testing.T) {
-	ports := servicePortRange()
-
-	require.Len(t, ports, 51)
-	assert.Equal(t, "443", ports[0].ContainerPort)
-	assert.Equal(t, "443", ports[0].HostPort)
-	assert.Equal(t, "4510", ports[1].ContainerPort)
-	assert.Equal(t, "4510", ports[1].HostPort)
-	assert.Equal(t, "4559", ports[50].ContainerPort)
-	assert.Equal(t, "4559", ports[50].HostPort)
+func TestFilterHostEnv(t *testing.T) {
+	input := []string{
+		"CI=true",
+		"LOCALSTACK_DISABLE_EVENTS=1",
+		"LOCALSTACK_API_ENDPOINT=https://example.test",
+		"LOCALSTACK_AUTH_TOKEN=host-token",
+		"PATH=/usr/bin",
+		"HOME=/home/user",
+		"CI_PIPELINE=foo",
+	}
+
+	got := filterHostEnv(input)
+
+	assert.Contains(t, got, "CI=true")
+	assert.Contains(t, got, "LOCALSTACK_DISABLE_EVENTS=1")
+	assert.Contains(t, got, "LOCALSTACK_API_ENDPOINT=https://example.test")
+	assert.NotContains(t, got, "LOCALSTACK_AUTH_TOKEN=host-token",
+		"host LOCALSTACK_AUTH_TOKEN must be filtered so it cannot overwrite the lstk-resolved token")
+	assert.NotContains(t, got, "PATH=/usr/bin")
+	assert.NotContains(t, got, "HOME=/home/user")
+	assert.NotContains(t, got, "CI_PIPELINE=foo", "only exact CI= must be forwarded, not CI_*")
 }
+
diff --git a/test/integration/start_test.go b/test/integration/start_test.go
index a95fd77..e67898e 100644
--- a/test/integration/start_test.go
+++ b/test/integration/start_test.go
@@ -226,14 +226,32 @@ func TestStartCommandSetsUpContainerCorrectly(t *testing.T) {
 	})
 }
 
-// containerEnvToMap converts a Docker container's []string env to a map.
-func containerEnvToMap(envList []string) map[string]string {
-	m := make(map[string]string, len(envList))
-	for _, e := range envList {
-		k, v, _ := strings.Cut(e, "=")
-		m[k] = v
-	}
-	return m
+func TestStartCommandPassesCIAndLocalStackEnvVars(t *testing.T) {
+	requireDocker(t)
+	_ = env.Require(t, env.AuthToken)
+
+	cleanup()
+	t.Cleanup(cleanup)
+
+	mockServer := createMockLicenseServer(true)
+	defer mockServer.Close()
+
+	ctx := testContext(t)
+	_, stderr, err := runLstk(t, ctx, "", env.With(env.APIEndpoint, mockServer.URL).
+		With(env.CI, "true").
+		With(env.DisableEvents, "1"),
+		"start")
+	require.NoError(t, err, "lstk start failed: %s", stderr)
+	requireExitCode(t, 0, err)
+
+	inspect, err := dockerClient.ContainerInspect(ctx, containerName)
+	require.NoError(t, err, "failed to inspect container")
+	require.True(t, inspect.State.Running)
+
+	envVars := containerEnvToMap(inspect.Config.Env)
+	assert.Equal(t, "true", envVars["CI"])
+	assert.Equal(t, "1", envVars["LOCALSTACK_DISABLE_EVENTS"])
+	assert.NotEmpty(t, envVars["LOCALSTACK_AUTH_TOKEN"])
 }
 
 // hasBindTarget checks if any bind mount targets the given container path.
@@ -247,6 +265,16 @@ func hasBindTarget(binds []string, containerPath string) bool {
 	return false
 }
 
+// containerEnvToMap converts a Docker container's []string env to a map.
+func containerEnvToMap(envList []string) map[string]string {
+	m := make(map[string]string, len(envList))
+	for _, e := range envList {
+		k, v, _ := strings.Cut(e, "=")
+		m[k] = v
+	}
+	return m
+}
+
 func cleanup() {
 	ctx := context.Background()
 	_ = dockerClient.ContainerStop(ctx, containerName, container.StopOptions{})