diff --git a/packages/runtime-dom/__tests__/helpers/useCssVars.spec.ts b/packages/runtime-dom/__tests__/helpers/useCssVars.spec.ts
new file mode 100644
index 00000000..b3407b34
--- /dev/null
+++ b/packages/runtime-dom/__tests__/helpers/useCssVars.spec.ts
@@ -0,0 +1,80 @@
+import {
+  render,
+  useCSSVars,
+  h,
+  reactive,
+  nextTick,
+  ComponentOptions
+} from '@vue/runtime-dom'
+
+describe('useCssVars', () => {
+  async function assertCssVars(
+    getApp: (state: any) => ComponentOptions,
+    scopeId?: string
+  ) {
+    const state = reactive({ color: 'red' })
+    const App = getApp(state)
+    const root = document.createElement('div')
+    const prefix = scopeId ? `${scopeId}-` : ``
+
+    render(h(App), root)
+    for (const c of [].slice.call(root.children as any)) {
+      expect((c as HTMLElement).style.getPropertyValue(`--${prefix}color`))
+    }
+
+    state.color = 'green'
+    await nextTick()
+    for (const c of [].slice.call(root.children as any)) {
+      expect((c as HTMLElement).style.getPropertyValue(`--${prefix}color`))
+    }
+  }
+
+  test('basic', async () => {
+    await assertCssVars(state => ({
+      setup() {
+        // test receiving render context
+        useCSSVars((ctx: any) => ({
+          color: ctx.color
+        }))
+        return state
+      },
+      render() {
+        return h('div')
+      }
+    }))
+  })
+
+  test('on fragment root', async () => {
+    await assertCssVars(state => ({
+      setup() {
+        useCSSVars(() => state)
+        return () => [h('div'), h('div')]
+      }
+    }))
+  })
+
+  test('on HOCs', async () => {
+    const Child = () => [h('div'), h('div')]
+
+    await assertCssVars(state => ({
+      setup() {
+        useCSSVars(() => state)
+        return () => h(Child)
+      }
+    }))
+  })
+
+  test('with scopeId', async () => {
+    const id = 'v-12345'
+
+    await assertCssVars(
+      state => ({
+        setup() {
+          useCSSVars(() => state, id)
+          return () => h('div')
+        }
+      }),
+      id
+    )
+  })
+})
diff --git a/packages/runtime-dom/src/helpers/useCssVars.ts b/packages/runtime-dom/src/helpers/useCssVars.ts
index bd2a7c6c..480598ae 100644
--- a/packages/runtime-dom/src/helpers/useCssVars.ts
+++ b/packages/runtime-dom/src/helpers/useCssVars.ts
@@ -10,7 +10,8 @@ import {
 import { ShapeFlags } from '@vue/shared/src'
 
 export function useCSSVars(
-  getter: (ctx: ComponentPublicInstance) => Record<string, string>
+  getter: (ctx: ComponentPublicInstance) => Record<string, string>,
+  scopeId?: string
 ) {
   const instance = getCurrentInstance()
   if (!instance) {
@@ -20,22 +21,27 @@ export function useCSSVars(
   }
   onMounted(() => {
     watchEffect(() => {
-      setVarsOnVNode(instance.vnode, getter(instance.proxy!))
+      setVarsOnVNode(instance.vnode, getter(instance.proxy!), scopeId)
     })
   })
 }
 
-function setVarsOnVNode(vnode: VNode, vars: Record<string, string>) {
+function setVarsOnVNode(
+  vnode: VNode,
+  vars: Record<string, string>,
+  scopeId?: string
+) {
   // drill down HOCs until it's a non-component vnode
   while (vnode.component) {
     vnode = vnode.component.subTree
   }
   if (vnode.shapeFlag & ShapeFlags.ELEMENT && vnode.el) {
     const style = vnode.el.style
+    const prefix = scopeId ? scopeId + '-' : ''
     for (const key in vars) {
-      style.setProperty(`--${key}`, vars[key])
+      style.setProperty(`--${prefix}${key}`, vars[key])
     }
   } else if (vnode.type === Fragment) {
-    ;(vnode.children as VNode[]).forEach(c => setVarsOnVNode(c, vars))
+    ;(vnode.children as VNode[]).forEach(c => setVarsOnVNode(c, vars, scopeId))
   }
 }