diff --git a/src/lib/litegraph/src/LGraph.test.ts b/src/lib/litegraph/src/LGraph.test.ts
index 1c2f38da2..0e0e0b07e 100644
--- a/src/lib/litegraph/src/LGraph.test.ts
+++ b/src/lib/litegraph/src/LGraph.test.ts
@@ -1,6 +1,10 @@
 import { describe, expect, it } from 'vitest'
 
 import { LGraph, LGraphNode, LiteGraph } from '@/lib/litegraph/src/litegraph'
+import {
+  createTestSubgraphData,
+  createTestSubgraphNode
+} from './subgraph/__fixtures__/subgraphHelpers'
 
 import { test } from './__fixtures__/testExtensions'
 
@@ -209,6 +213,70 @@ describe('Graph Clearing and Callbacks', () => {
   })
 })
 
+describe('Subgraph Definition Garbage Collection', () => {
+  function createSubgraphWithNodes(rootGraph: LGraph, nodeCount: number) {
+    const subgraph = rootGraph.createSubgraph(createTestSubgraphData())
+
+    const innerNodes: LGraphNode[] = []
+    for (let i = 0; i < nodeCount; i++) {
+      const node = new LGraphNode(`Inner Node ${i}`)
+      subgraph.add(node)
+      innerNodes.push(node)
+    }
+
+    return { subgraph, innerNodes }
+  }
+
+  it('removing SubgraphNode fires onRemoved for inner nodes', () => {
+    const rootGraph = new LGraph()
+    const { subgraph, innerNodes } = createSubgraphWithNodes(rootGraph, 2)
+    const removedNodeIds = new Set<string>()
+
+    for (const node of innerNodes) {
+      node.onRemoved = () => removedNodeIds.add(String(node.id))
+    }
+
+    const subgraphNode = createTestSubgraphNode(subgraph, { pos: [100, 100] })
+    rootGraph.add(subgraphNode)
+
+    expect(subgraph.nodes.length).toBe(2)
+
+    rootGraph.remove(subgraphNode)
+
+    expect(removedNodeIds.size).toBe(2)
+  })
+
+  it('removing SubgraphNode fires onNodeRemoved callback', () => {
+    const rootGraph = new LGraph()
+    const { subgraph } = createSubgraphWithNodes(rootGraph, 2)
+    const graphRemovedNodeIds = new Set<string>()
+
+    subgraph.onNodeRemoved = (node) => graphRemovedNodeIds.add(String(node.id))
+
+    const subgraphNode = createTestSubgraphNode(subgraph, { pos: [100, 100] })
+    rootGraph.add(subgraphNode)
+
+    rootGraph.remove(subgraphNode)
+
+    expect(graphRemovedNodeIds.size).toBe(2)
+  })
+
+  it('subgraph definition is removed when SubgraphNode is removed', () => {
+    const rootGraph = new LGraph()
+    const { subgraph } = createSubgraphWithNodes(rootGraph, 1)
+    const subgraphId = subgraph.id
+
+    const subgraphNode = createTestSubgraphNode(subgraph, { pos: [100, 100] })
+    rootGraph.add(subgraphNode)
+
+    expect(rootGraph.subgraphs.has(subgraphId)).toBe(true)
+
+    rootGraph.remove(subgraphNode)
+
+    expect(rootGraph.subgraphs.has(subgraphId)).toBe(false)
+  })
+})
+
 describe('Legacy LGraph Compatibility Layer', () => {
   test('can be extended via prototype', ({ expect, minimalGraph }) => {
     // @ts-expect-error Should always be an error.
diff --git a/src/lib/litegraph/src/LGraph.ts b/src/lib/litegraph/src/LGraph.ts
index 486831e13..28f877163 100644
--- a/src/lib/litegraph/src/LGraph.ts
+++ b/src/lib/litegraph/src/LGraph.ts
@@ -985,6 +985,16 @@ export class LGraph
       }
     }
 
+    // Subgraph cleanup (use local const to avoid type narrowing affecting node.graph assignment)
+    const subgraphNode = node.isSubgraphNode() ? node : null
+    if (subgraphNode) {
+      for (const innerNode of subgraphNode.subgraph.nodes) {
+        innerNode.onRemoved?.()
+        subgraphNode.subgraph.onNodeRemoved?.(innerNode)
+      }
+      this.rootGraph.subgraphs.delete(subgraphNode.subgraph.id)
+    }
+
     // callback
     node.onRemoved?.()