diff --git a/src/plugins/platforms/wasm/qwasmcompositor.cpp b/src/plugins/platforms/wasm/qwasmcompositor.cpp
index 5c5fc80adba..bfcb1a9fe58 100644
--- a/src/plugins/platforms/wasm/qwasmcompositor.cpp
+++ b/src/plugins/platforms/wasm/qwasmcompositor.cpp
@@ -115,7 +115,7 @@ QWasmCompositor::~QWasmCompositor()
 
 void QWasmCompositor::deregisterEventHandlers()
 {
-    QByteArray canvasSelector = "#" + screen()->canvasId().toUtf8();
+    QByteArray canvasSelector = screen()->canvasTargetId().toUtf8();
     emscripten_set_keydown_callback(canvasSelector.constData(), 0, 0, NULL);
     emscripten_set_keyup_callback(canvasSelector.constData(),  0, 0, NULL);
 
@@ -156,7 +156,7 @@ void QWasmCompositor::destroy()
 
 void QWasmCompositor::initEventHandlers()
 {
-    QByteArray canvasSelector = "#" + screen()->canvasId().toUtf8();
+    QByteArray canvasSelector = screen()->canvasTargetId().toUtf8();
 
     eventTranslator->g_usePlatformMacSpecifics
     = (QWasmIntegration::get()->platform == QWasmIntegration::MacOSPlatform);
diff --git a/src/plugins/platforms/wasm/qwasmopenglcontext.cpp b/src/plugins/platforms/wasm/qwasmopenglcontext.cpp
index c122335a575..4462e55524a 100644
--- a/src/plugins/platforms/wasm/qwasmopenglcontext.cpp
+++ b/src/plugins/platforms/wasm/qwasmopenglcontext.cpp
@@ -87,13 +87,12 @@ bool QWasmOpenGLContext::maybeCreateEmscriptenContext(QPlatformSurface *surface)
     if (m_context)
         return m_screen == screen;
 
-    QString canvasId = QWasmScreen::get(screen)->canvasId();
-    m_context = createEmscriptenContext(canvasId, m_requestedFormat);
+    m_context = createEmscriptenContext(QWasmScreen::get(screen)->canvasTargetId(), m_requestedFormat);
     m_screen = screen;
     return true;
 }
 
-EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(const QString &canvasId, QSurfaceFormat format)
+EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(const QString &canvasTargetId, QSurfaceFormat format)
 {
     EmscriptenWebGLContextAttributes attributes;
     emscripten_webgl_init_context_attributes(&attributes); // Populate with default attributes
@@ -114,7 +113,7 @@ EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(cons
     attributes.depth = useDepthStencil;
     attributes.stencil = useDepthStencil;
 
-    QByteArray convasSelector = "#" + canvasId.toUtf8();
+    QByteArray convasSelector = canvasTargetId.toUtf8();
     EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context(convasSelector.constData(), &attributes);
 
     return context;
diff --git a/src/plugins/platforms/wasm/qwasmscreen.cpp b/src/plugins/platforms/wasm/qwasmscreen.cpp
index 52da924f8ff..c32adbe13fd 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.cpp
+++ b/src/plugins/platforms/wasm/qwasmscreen.cpp
@@ -68,7 +68,8 @@ QWasmScreen::QWasmScreen(const emscripten::val &containerOrCanvas)
         // Create the canvas (for the correct document) as a child of the container
         m_canvas = containerOrCanvas["ownerDocument"].call<emscripten::val>("createElement", std::string("canvas"));
         containerOrCanvas.call<void>("appendChild", m_canvas);
-        m_canvas.set("id", std::string("qtcanvas_") + std::to_string(uint32_t(this)));
+        std::string screenId = std::string("qtcanvas_") + std::to_string(uint32_t(this));
+        m_canvas.set("id", screenId);
 
         // Make the canvas occupy 100% of parent
         emscripten::val style = m_canvas["style"];
@@ -96,6 +97,16 @@ QWasmScreen::QWasmScreen(const emscripten::val &containerOrCanvas)
     m_onContextMenu = std::make_unique<qstdweb::EventCallback>(m_canvas, "contextmenu", [](emscripten::val event){
         event.call<void>("preventDefault");
     });
+    
+    // Create "specialHTMLTargets" mapping for the canvas. Normally, Emscripten
+    // uses the html element id when targeting elements, for example when registering
+    // event callbacks. However, this approach is limited to supporting single-document
+    // apps/ages only, since Emscripten uses the main document to look up the element.
+    // As a workaround for this, Emscripten supports registering custom mappings in the
+    // "specialHTMLTargets" object. Add a mapping for the canvas for this screen.
+    EM_ASM({
+        specialHTMLTargets["!qtcanvas_" + $0] = Emval.toValue($1);
+    }, uint32_t(this), m_canvas.as_handle());
 
     // Install event handlers on the container/canvas. This must be
     // done after the canvas has been created above.
@@ -107,6 +118,10 @@ QWasmScreen::QWasmScreen(const emscripten::val &containerOrCanvas)
 
 QWasmScreen::~QWasmScreen()
 {
+    EM_ASM({
+        specialHTMLTargets["!qtcanvas_" + $0] = undefined;
+    }, uint32_t(this));
+
     m_canvas.set(m_canvasResizeObserverCallbackContextPropertyName, emscripten::val(intptr_t(0)));
     destroy();
 }
@@ -146,11 +161,21 @@ emscripten::val QWasmScreen::canvas() const
     return m_canvas;
 }
 
+// Returns the html element id for the screen's canvas.
 QString QWasmScreen::canvasId() const
 {
     return QWasmString::toQString(m_canvas["id"]);
 }
 
+// Returns the canvas _target_ id, for use with Emscripten's
+// event registration functions. The target id is a globally
+// unique id, unlike the html element id which is only unique
+// within one html document. See specialHtmlTargets.
+QString QWasmScreen::canvasTargetId() const
+{
+    return QStringLiteral("!qtcanvas_") + QString::number(int32_t(this));
+}
+
 QRect QWasmScreen::geometry() const
 {
     return m_geometry;
@@ -246,7 +271,7 @@ void QWasmScreen::updateQScreenAndCanvasRenderSize()
     // Setting the render size to a value larger than the CSS size enables high-dpi
     // rendering.
 
-    QByteArray canvasSelector = "#" + canvasId().toUtf8();
+    QByteArray canvasSelector = canvasTargetId().toUtf8();
     double css_width;
     double css_height;
     emscripten_get_element_css_size(canvasSelector.constData(), &css_width, &css_height);
diff --git a/src/plugins/platforms/wasm/qwasmscreen.h b/src/plugins/platforms/wasm/qwasmscreen.h
index 4fb387f10a2..07f52f9fdcf 100644
--- a/src/plugins/platforms/wasm/qwasmscreen.h
+++ b/src/plugins/platforms/wasm/qwasmscreen.h
@@ -62,6 +62,7 @@ public:
     emscripten::val container() const;
     emscripten::val canvas() const;
     QString canvasId() const;
+    QString canvasTargetId() const;
 
     QWasmCompositor *compositor();
     QWasmEventTranslator *eventTranslator();