diff --git a/v3/internal/commands/task_wrapper.go b/v3/internal/commands/task_wrapper.go
index fbbc715494b..38cbcddb621 100644
--- a/v3/internal/commands/task_wrapper.go
+++ b/v3/internal/commands/task_wrapper.go
@@ -21,6 +21,18 @@ var validPlatforms = map[string]bool{
 	"linux":   true,
 }
 
+// rootDispatchTasks are the verbs that have a top-level task in the generated
+// root Taskfile which dispatches to the platform-specific task via the GOOS
+// variable (e.g. `build` -> `{{.GOOS}}:build`). For these we run the root task
+// and pass GOOS as a variable, so user customisations in the root Taskfile are
+// honoured for both native and cross-compilation builds. Verbs absent here
+// (e.g. `sign`, which only exists per-platform) always target the
+// platform-specific task directly.
+var rootDispatchTasks = map[string]bool{
+	"build":   true,
+	"package": true,
+}
+
 func Build(buildFlags *flags.Build, otherArgs []string) error {
 	if buildFlags.Tags != "" {
 		otherArgs = append(otherArgs, "EXTRA_TAGS="+buildFlags.Tags)
@@ -86,15 +98,28 @@ func wrapTask(action string, otherArgs []string) error {
 		}
 	}
 
-	taskName := action
+	// platformTaskName always targets the platform-specific task (e.g.
+	// "linux:build"). The experimental wake runner is built against this concrete
+	// name, so it keeps using it unconditionally.
+	platformTaskName := action
 	if validPlatforms[goos] {
-		taskName = goos + ":" + action
+		platformTaskName = goos + ":" + action
 	}
 
-	remainingArgs = append(remainingArgs, "ARCH="+goarch)
+	// Pass GOOS/ARCH through as Taskfile variables. The root build/package/run
+	// tasks dispatch on {{.GOOS}}, so running the root task (rather than the
+	// platform-prefixed one) means any customisations in the root Taskfile are
+	// honoured, for both native and cross-compilation builds. Verbs without a
+	// root task (e.g. `sign`) still target the platform task directly. See #5615.
+	remainingArgs = append(remainingArgs, "GOOS="+goos, "ARCH="+goarch)
+
+	taskName := platformTaskName
+	if rootDispatchTasks[action] {
+		taskName = action
+	}
 
 	if useWake() {
-		return runWakeTask(action, taskName, goos, goarch, remainingArgs)
+		return runWakeTask(action, platformTaskName, goos, goarch, remainingArgs)
 	}
 
 	newArgs := []string{"wails3", "task", taskName}
diff --git a/v3/internal/commands/task_wrapper_test.go b/v3/internal/commands/task_wrapper_test.go
index b9c059f11a8..c884afe3e2c 100644
--- a/v3/internal/commands/task_wrapper_test.go
+++ b/v3/internal/commands/task_wrapper_test.go
@@ -14,6 +14,13 @@ func TestWrapTask(t *testing.T) {
 	currentOS := runtime.GOOS
 	currentArch := runtime.GOARCH
 
+	// foreignOS is a GOOS guaranteed to differ from the host, so cross-compile
+	// cases are exercised regardless of which platform the test runs on.
+	foreignOS := "windows"
+	if currentOS == "windows" {
+		foreignOS = "linux"
+	}
+
 	tests := []struct {
 		name             string
 		command          string
@@ -25,70 +32,88 @@ func TestWrapTask(t *testing.T) {
 		expectedOsArgs   []string
 	}{
 		{
-			name:             "Build with parameters uses current platform",
+			// Host-OS build runs the root Taskfile's `build` task (not the
+			// platform-prefixed one) so root customisations are honoured. The
+			// root task dispatches via the GOOS variable we pass through (#5615).
+			name:             "Host build runs root build task",
 			command:          "build",
 			otherArgs:        []string{"CONFIG=debug"},
-			expectedTaskName: currentOS + ":build",
-			expectedArgs:     []string{"CONFIG=debug", "ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", currentOS + ":build", "CONFIG=debug", "ARCH=" + currentArch},
+			expectedTaskName: "build",
+			expectedArgs:     []string{"CONFIG=debug", "GOOS=" + currentOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "build", "CONFIG=debug", "GOOS=" + currentOS, "ARCH=" + currentArch},
 		},
 		{
-			name:             "Package with parameters uses current platform",
+			name:             "Host package runs root package task",
 			command:          "package",
 			otherArgs:        []string{"VERSION=1.0.0", "OUTPUT=app.pkg"},
-			expectedTaskName: currentOS + ":package",
-			expectedArgs:     []string{"VERSION=1.0.0", "OUTPUT=app.pkg", "ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", currentOS + ":package", "VERSION=1.0.0", "OUTPUT=app.pkg", "ARCH=" + currentArch},
+			expectedTaskName: "package",
+			expectedArgs:     []string{"VERSION=1.0.0", "OUTPUT=app.pkg", "GOOS=" + currentOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "package", "VERSION=1.0.0", "OUTPUT=app.pkg", "GOOS=" + currentOS, "ARCH=" + currentArch},
 		},
 		{
-			name:             "Build without parameters",
+			name:             "Host build without parameters runs root build task",
 			command:          "build",
 			otherArgs:        []string{},
-			expectedTaskName: currentOS + ":build",
-			expectedArgs:     []string{"ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", currentOS + ":build", "ARCH=" + currentArch},
+			expectedTaskName: "build",
+			expectedArgs:     []string{"GOOS=" + currentOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "build", "GOOS=" + currentOS, "ARCH=" + currentArch},
 		},
 		{
-			name:             "GOOS override changes task prefix",
+			// sign has no root dispatch task, so it always targets the platform.
+			name:             "Sign always targets platform task",
+			command:          "sign",
+			otherArgs:        []string{"IDENTITY=Developer ID"},
+			expectedTaskName: currentOS + ":sign",
+			expectedArgs:     []string{"IDENTITY=Developer ID", "GOOS=" + currentOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", currentOS + ":sign", "IDENTITY=Developer ID", "GOOS=" + currentOS, "ARCH=" + currentArch},
+		},
+		{
+			// Cross-OS build still runs the root `build` task; the GOOS variable
+			// carries the target so the root Taskfile dispatches to it.
+			name:             "Cross-OS GOOS override runs root build task with GOOS var",
 			command:          "build",
-			otherArgs:        []string{"GOOS=darwin", "CONFIG=release"},
-			expectedTaskName: "darwin:build",
-			expectedArgs:     []string{"CONFIG=release", "ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", "darwin:build", "CONFIG=release", "ARCH=" + currentArch},
+			otherArgs:        []string{"GOOS=" + foreignOS, "CONFIG=release"},
+			expectedTaskName: "build",
+			expectedArgs:     []string{"CONFIG=release", "GOOS=" + foreignOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "build", "CONFIG=release", "GOOS=" + foreignOS, "ARCH=" + currentArch},
 		},
 		{
-			name:             "GOARCH override changes ARCH arg",
+			// GOARCH alone (cross-arch, same OS) runs the root task; the root
+			// dispatch passes GOOS/ARCH through to the platform build.
+			name:             "GOARCH-only override runs root build task",
 			command:          "build",
 			otherArgs:        []string{"GOARCH=arm64"},
-			expectedTaskName: currentOS + ":build",
-			expectedArgs:     []string{"ARCH=arm64"},
-			expectedOsArgs:   []string{"wails3", "task", currentOS + ":build", "ARCH=arm64"},
+			expectedTaskName: "build",
+			expectedArgs:     []string{"GOOS=" + currentOS, "ARCH=arm64"},
+			expectedOsArgs:   []string{"wails3", "task", "build", "GOOS=" + currentOS, "ARCH=arm64"},
 		},
 		{
-			name:             "Both GOOS and GOARCH override",
+			name:             "Cross-OS GOOS and GOARCH override",
 			command:          "package",
-			otherArgs:        []string{"GOOS=windows", "GOARCH=386", "VERSION=2.0"},
-			expectedTaskName: "windows:package",
-			expectedArgs:     []string{"VERSION=2.0", "ARCH=386"},
-			expectedOsArgs:   []string{"wails3", "task", "windows:package", "VERSION=2.0", "ARCH=386"},
+			otherArgs:        []string{"GOOS=" + foreignOS, "GOARCH=386", "VERSION=2.0"},
+			expectedTaskName: "package",
+			expectedArgs:     []string{"VERSION=2.0", "GOOS=" + foreignOS, "ARCH=386"},
+			expectedOsArgs:   []string{"wails3", "task", "package", "VERSION=2.0", "GOOS=" + foreignOS, "ARCH=386"},
 		},
 		{
-			name:             "Environment GOOS is used when no arg override",
+			name:             "Environment GOOS (cross) is used when no arg override",
 			command:          "build",
 			otherArgs:        []string{"CONFIG=debug"},
-			envGOOS:          "darwin",
-			expectedTaskName: "darwin:build",
-			expectedArgs:     []string{"CONFIG=debug", "ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", "darwin:build", "CONFIG=debug", "ARCH=" + currentArch},
+			envGOOS:          foreignOS,
+			expectedTaskName: "build",
+			expectedArgs:     []string{"CONFIG=debug", "GOOS=" + foreignOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "build", "CONFIG=debug", "GOOS=" + foreignOS, "ARCH=" + currentArch},
 		},
 		{
+			// Arg GOOS takes precedence over the GOOS environment variable; the
+			// passed-through GOOS var reflects the arg value.
 			name:             "Arg GOOS overrides environment GOOS",
 			command:          "build",
-			otherArgs:        []string{"GOOS=linux"},
+			otherArgs:        []string{"GOOS=" + foreignOS},
 			envGOOS:          "darwin",
-			expectedTaskName: "linux:build",
-			expectedArgs:     []string{"ARCH=" + currentArch},
-			expectedOsArgs:   []string{"wails3", "task", "linux:build", "ARCH=" + currentArch},
+			expectedTaskName: "build",
+			expectedArgs:     []string{"GOOS=" + foreignOS, "ARCH=" + currentArch},
+			expectedOsArgs:   []string{"wails3", "task", "build", "GOOS=" + foreignOS, "ARCH=" + currentArch},
 		},
 	}
 
@@ -195,8 +220,8 @@ func TestBuildCommand(t *testing.T) {
 
 	err := Build(buildFlags, otherArgs)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":build", capturedOptions.Name)
-	assert.Equal(t, []string{"CONFIG=release", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "build", capturedOptions.Name)
+	assert.Equal(t, []string{"CONFIG=release", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestBuildCommandWithTags(t *testing.T) {
@@ -244,8 +269,8 @@ func TestBuildCommandWithTags(t *testing.T) {
 
 	err := Build(buildFlags, otherArgs)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":build", capturedOptions.Name)
-	assert.Equal(t, []string{"CONFIG=release", "EXTRA_TAGS=gtk4", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "build", capturedOptions.Name)
+	assert.Equal(t, []string{"CONFIG=release", "EXTRA_TAGS=gtk4", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestBuildCommandWithMultipleTags(t *testing.T) {
@@ -292,8 +317,8 @@ func TestBuildCommandWithMultipleTags(t *testing.T) {
 
 	err := Build(buildFlags, nil)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":build", capturedOptions.Name)
-	assert.Equal(t, []string{"EXTRA_TAGS=gtk4,server", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "build", capturedOptions.Name)
+	assert.Equal(t, []string{"EXTRA_TAGS=gtk4,server", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestBuildCommandWithObfuscation(t *testing.T) {
@@ -342,8 +367,8 @@ func TestBuildCommandWithObfuscation(t *testing.T) {
 
 	err := Build(buildFlags, nil)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":build", capturedOptions.Name)
-	assert.Equal(t, []string{"EXTRA_TAGS=gtk4", "OBFUSCATED=true", "GARBLE_ARGS=-literals -tiny", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "build", capturedOptions.Name)
+	assert.Equal(t, []string{"EXTRA_TAGS=gtk4", "OBFUSCATED=true", "GARBLE_ARGS=-literals -tiny", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestBuildCommandWithoutTags(t *testing.T) {
@@ -389,8 +414,8 @@ func TestBuildCommandWithoutTags(t *testing.T) {
 
 	err := Build(buildFlags, nil)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":build", capturedOptions.Name)
-	assert.Equal(t, []string{"ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "build", capturedOptions.Name)
+	assert.Equal(t, []string{"GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestPackageCommand(t *testing.T) {
@@ -437,8 +462,8 @@ func TestPackageCommand(t *testing.T) {
 
 	err := Package(packageFlags, otherArgs)
 	assert.NoError(t, err)
-	assert.Equal(t, currentOS+":package", capturedOptions.Name)
-	assert.Equal(t, []string{"VERSION=2.0.0", "OUTPUT=myapp.dmg", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, "package", capturedOptions.Name)
+	assert.Equal(t, []string{"VERSION=2.0.0", "OUTPUT=myapp.dmg", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
 
 func TestSignWrapperCommand(t *testing.T) {
@@ -486,5 +511,5 @@ func TestSignWrapperCommand(t *testing.T) {
 	err := SignWrapper(signFlags, otherArgs)
 	assert.NoError(t, err)
 	assert.Equal(t, currentOS+":sign", capturedOptions.Name)
-	assert.Equal(t, []string{"IDENTITY=Developer ID", "ARCH=" + currentArch}, capturedOtherArgs)
+	assert.Equal(t, []string{"IDENTITY=Developer ID", "GOOS=" + currentOS, "ARCH=" + currentArch}, capturedOtherArgs)
 }
diff --git a/v3/internal/templates/_common/Taskfile.tmpl.yml b/v3/internal/templates/_common/Taskfile.tmpl.yml
index 89bbaa86c48..fd99895899f 100644
--- a/v3/internal/templates/_common/Taskfile.tmpl.yml
+++ b/v3/internal/templates/_common/Taskfile.tmpl.yml
@@ -5,6 +5,10 @@ vars:
   BIN_DIR: "bin"
   PACKAGE_MANAGER: '{{.Opn}}.PACKAGE_MANAGER | default "npm"{{.Cls}}'
   VITE_PORT: '{{.Opn}}.WAILS_VITE_PORT | default 9245{{.Cls}}'
+  # Target OS for build/package/run. Defaults to the host OS, and is overridden
+  # by `wails3 build GOOS=...` (or the GOOS env var) for cross-compilation. The
+  # tasks below dispatch to the matching platform Taskfile via this variable.
+  GOOS: '{{.Opn}}.GOOS | default OS{{.Cls}}'
 
 includes:
   common: ./build/Taskfile.yml
@@ -18,17 +22,17 @@ tasks:
   build:
     summary: Builds the application
     cmds:
-      - task: "{{.Opn}}OS{{.Cls}}:build"
+      - task: "{{.Opn}}.GOOS{{.Cls}}:build"
 
   package:
     summary: Packages a production build of the application
     cmds:
-      - task: "{{.Opn}}OS{{.Cls}}:package"
+      - task: "{{.Opn}}.GOOS{{.Cls}}:package"
 
   run:
     summary: Runs the application
     cmds:
-      - task: "{{.Opn}}OS{{.Cls}}:run"
+      - task: "{{.Opn}}.GOOS{{.Cls}}:run"
 
   dev:
     summary: Runs the application in development mode
diff --git a/v3/internal/templates/taskfile_template_test.go b/v3/internal/templates/taskfile_template_test.go
index 58bfb9f933d..f78fb625839 100644
--- a/v3/internal/templates/taskfile_template_test.go
+++ b/v3/internal/templates/taskfile_template_test.go
@@ -17,3 +17,24 @@ func TestCommonTaskfileUsesBinaryName(t *testing.T) {
 	assert.False(t, strings.Contains(content, `{{.ProjectName}}`),
 		"root Taskfile template should not fall back to {{.ProjectName}} for APP_NAME")
 }
+
+// TestCommonTaskfileDispatchesViaGOOS guards the fix for #5615: the root
+// build/package/run tasks must dispatch to the platform Taskfile via the GOOS
+// variable (so `wails3 build`/`dev`/`package` run the root task and honour any
+// customisations there, for both native and cross builds), rather than the
+// built-in {{OS}} which the CLI used to bypass with an OS-prefixed task name.
+func TestCommonTaskfileDispatchesViaGOOS(t *testing.T) {
+	data, err := templates.ReadFile("_common/Taskfile.tmpl.yml")
+	require.NoError(t, err, "_common/Taskfile.tmpl.yml should be present in embedded templates")
+	// Note: the template escapes literal go-task delimiters via {{.Opn}}/{{.Cls}},
+	// so the rendered output contains `{{.GOOS}}` rather than the raw text here.
+	content := string(data)
+	for _, verb := range []string{"build", "package", "run"} {
+		assert.Contains(t, content, `{{.Opn}}.GOOS{{.Cls}}:`+verb,
+			"root Taskfile %s task should dispatch via {{.GOOS}}", verb)
+	}
+	assert.Contains(t, content, `GOOS: '{{.Opn}}.GOOS | default OS{{.Cls}}'`,
+		"root Taskfile should define a GOOS var defaulting to the host OS")
+	assert.NotContains(t, content, `{{.Opn}}OS{{.Cls}}:`,
+		"root Taskfile should not dispatch via the {{OS}} built-in (bypassed by the CLI)")
+}