diff --git a/.changeset/read-only-bun-sqlite.md b/.changeset/read-only-bun-sqlite.md
new file mode 100644
index 00000000000..9037b67ad05
--- /dev/null
+++ b/.changeset/read-only-bun-sqlite.md
@@ -0,0 +1,5 @@
+---
+"@effect/sql-sqlite-bun": patch
+---
+
+Enforce read-only mode when opening Bun SQLite databases.
diff --git a/packages/sql/sqlite-bun/src/SqliteClient.ts b/packages/sql/sqlite-bun/src/SqliteClient.ts
index 5e7195fb264..745f12a5dab 100644
--- a/packages/sql/sqlite-bun/src/SqliteClient.ts
+++ b/packages/sql/sqlite-bun/src/SqliteClient.ts
@@ -115,14 +115,15 @@ export const make = (
       undefined
 
     const makeConnection = Effect.gen(function*() {
+      const readonly = options.readonly === true
       const db = new Database(options.filename, {
-        readonly: options.readonly,
-        readwrite: options.readwrite ?? true,
-        create: options.create ?? true
+        readonly,
+        readwrite: readonly ? false : options.readwrite ?? true,
+        create: readonly ? false : options.create ?? true
       } as any)
       yield* Effect.addFinalizer(() => Effect.sync(() => db.close()))
 
-      if (options.disableWAL !== true) {
+      if (options.disableWAL !== true && !readonly) {
         db.run("PRAGMA journal_mode = WAL;")
       }
 
diff --git a/packages/sql/sqlite-bun/test/Client.test.ts b/packages/sql/sqlite-bun/test/Client.test.ts
index fc3285a3604..82259957333 100644
--- a/packages/sql/sqlite-bun/test/Client.test.ts
+++ b/packages/sql/sqlite-bun/test/Client.test.ts
@@ -1,6 +1,35 @@
-import { describe, it } from "@effect/vitest"
+import { assert, describe, it } from "@effect/vitest"
 import { Effect } from "effect"
+import { Reactivity } from "effect/unstable/reactivity"
+import { rm } from "node:fs/promises"
+
+const isBun = "bun" in process.versions
 
 describe("Client", () => {
   it.effect("should work", () => Effect.void)
+
+  it.effect.skipIf(!isBun)("readonly clients reject writes", () =>
+    Effect.gen(function*() {
+      const { SqliteClient } = yield* Effect.promise(() => import("@effect/sql-sqlite-bun"))
+      const filename = `/tmp/effect-sqlite-bun-readonly-${crypto.randomUUID()}.db`
+      yield* Effect.acquireRelease(
+        Effect.void,
+        () => Effect.promise(() => rm(filename, { force: true }))
+      )
+
+      yield* Effect.scoped(
+        Effect.gen(function*() {
+          const sql = yield* SqliteClient.make({ filename })
+          yield* sql`CREATE TABLE test (id INTEGER PRIMARY KEY)`
+        })
+      )
+
+      const sql = yield* SqliteClient.make({ filename, readonly: true })
+      assert.deepStrictEqual(yield* sql`SELECT * FROM test`, [])
+
+      const error = yield* Effect.flip(sql`INSERT INTO test DEFAULT VALUES`)
+      assert.strictEqual(error._tag, "SqlError")
+      assert(error.reason.cause instanceof Error)
+      assert.match(error.reason.cause.message, /attempt to write a readonly database/i)
+    }).pipe(Effect.provide(Reactivity.layer)))
 })