diff --git a/packages/pglite/src/types.ts b/packages/pglite/src/types.ts
index dec8a9388..786eac52f 100644
--- a/packages/pglite/src/types.ts
+++ b/packages/pglite/src/types.ts
@@ -112,7 +112,9 @@ export const types = {
       if (typeof x === 'string') {
         return x
       } else {
-        return JSON_stringify(x)
+        return JSON_stringify(x, (_key: string, value: unknown) =>
+          typeof value === 'bigint' ? value.toString() : value,
+        )
       }
     },
     parse: (x: string) => JSON_parse(x),
diff --git a/packages/pglite/tests/types.test.ts b/packages/pglite/tests/types.test.ts
index 05aba06ff..e79a5c8b6 100644
--- a/packages/pglite/tests/types.test.ts
+++ b/packages/pglite/tests/types.test.ts
@@ -144,7 +144,31 @@ describe('serialize', () => {
     )
   })
 
-  it('not blob', () => {
-    expect(() => types.serializers[17](1)).toThrow()
+
+  it('json with bigint value', () => {
+    // BigInt values nested inside JSON objects must serialize to their string
+    // representation rather than throwing "Do not know how to serialize a BigInt"
+    // See https://github.com/electric-sql/pglite/issues/899
+    expect(types.serializers[114]({ id: 1n })).toEqual('{"id":"1"}')
+  })
+
+  it('json with nested bigint in array', () => {
+    expect(
+      types.serializers[114]([{ id: 1n, name: 'a' }, { id: 2n, name: 'b' }]),
+    ).toEqual('[{"id":"1","name":"a"},{"id":"2","name":"b"}]')
+  })
+
+  it('jsonb with bigint value', () => {
+    expect(types.serializers[3802]({ id: 1n })).toEqual('{"id":"1"}')
+  })
+
+  it('json number values are unchanged', () => {
+    // Regular numbers must still serialize as numbers, not strings
+    expect(types.serializers[114]({ id: 1 })).toEqual('{"id":1}')
+  })
+
+  it('json string passthrough unchanged', () => {
+    // Pre-serialized JSON strings must pass through as-is
+    expect(types.serializers[114]('{"id":1}')).toEqual('{"id":1}')
   })
 })