diff --git a/src/commands/init.ts b/src/commands/init.ts
index a436274..f5f0c25 100644
--- a/src/commands/init.ts
+++ b/src/commands/init.ts
@@ -8,7 +8,7 @@ import { DEFAULT_PRISMIC_HOST, env } from "../env";
 import { openBrowser } from "../lib/browser";
 import { CommandError, createCommand, type CommandConfig } from "../lib/command";
 import { diffArrays } from "../lib/diff";
-import { installDependencies } from "../lib/packageJson";
+import { installDependencies, readPackageJson, removeDependencies } from "../lib/packageJson";
 import { ForbiddenRequestError, UnauthorizedRequestError } from "../lib/request";
 import {
 	createConfig,
@@ -146,6 +146,17 @@ export default createCommand(config, async ({ values }) => {
 		try {
 			await deleteLegacySliceMachineConfig();
 		} catch {}
+		// Slice Machine is replaced by the Type Builder and CLI, so its packages
+		// are no longer needed after migrating.
+		const { dependencies, devDependencies, peerDependencies } = await readPackageJson();
+		const sliceMachinePackages = Object.keys({
+			...dependencies,
+			...devDependencies,
+			...peerDependencies,
+		}).filter((name) => name === "slice-machine-ui" || name.startsWith("@slicemachine/adapter-"));
+		if (sliceMachinePackages.length > 0) {
+			await removeDependencies(sliceMachinePackages);
+		}
 		console.info("Migrated slicemachine.config.json to prismic.config.json");
 	}
 
diff --git a/src/lib/packageJson.ts b/src/lib/packageJson.ts
index acc0c37..9b71f11 100644
--- a/src/lib/packageJson.ts
+++ b/src/lib/packageJson.ts
@@ -47,6 +47,19 @@ export async function addDependencies(dependencies: Record<string, string>): Pro
 	await writeFile(packageJsonPath, newContents);
 }
 
+export async function removeDependencies(names: string[]): Promise<void> {
+	const packageJsonPath = await findPackageJson();
+	const raw = await readFile(packageJsonPath, "utf8");
+	const indent = detectIndent(raw).indent || "\t";
+	const packageJson = JSON.parse(raw);
+	for (const section of ["dependencies", "devDependencies", "peerDependencies"]) {
+		if (!packageJson[section]) continue;
+		for (const name of names) delete packageJson[section][name];
+	}
+	const newContents = JSON.stringify(packageJson, null, indent) + "\n";
+	await writeFile(packageJsonPath, newContents);
+}
+
 export async function getNpmPackageVersion(name: string, tag = "latest"): Promise<string> {
 	const url = new URL(`${name}/${tag}`, "https://registry.npmjs.org/");
 	const { version } = await request(url, {
diff --git a/test/init.test.ts b/test/init.test.ts
index 78a4efb..f7943bb 100644
--- a/test/init.test.ts
+++ b/test/init.test.ts
@@ -148,6 +148,41 @@ it("migrates slicemachine.config.json", async ({ expect, project, prismic, repo
 	await expect(access(new URL("slicemachine.config.json", project))).rejects.toThrow();
 });
 
+it("uninstalls Slice Machine packages when migrating", async ({
+	expect,
+	project,
+	prismic,
+	repo,
+}) => {
+	await rm(new URL("prismic.config.json", project));
+	await writeFile(
+		new URL("package.json", project),
+		JSON.stringify({
+			dependencies: { next: "latest" },
+			devDependencies: {
+				"slice-machine-ui": "^2.0.0",
+				// A non-matching adapter, to verify any @slicemachine/adapter-* is removed.
+				"@slicemachine/adapter-nuxt": "^0.3.0",
+			},
+		}),
+	);
+	await writeFile(
+		new URL("slicemachine.config.json", project),
+		JSON.stringify({ repositoryName: repo, libraries: ["./src/slices"] }),
+	);
+
+	const proc = prismic("init");
+	const output = captureOutput(proc);
+	await expect.poll(output, { timeout: 15_000 }).toContain("Migrated slicemachine.config.json");
+	proc.kill();
+
+	const packageJson = JSON.parse(await readFile(new URL("package.json", project), "utf-8"));
+	const allDependencies = { ...packageJson.dependencies, ...packageJson.devDependencies };
+	expect(allDependencies).not.toHaveProperty("slice-machine-ui");
+	expect(allDependencies).not.toHaveProperty("@slicemachine/adapter-nuxt");
+	expect(allDependencies).toHaveProperty("next");
+});
+
 it("fails when Type Builder is not enabled", async ({ expect, project, prismic, repo }) => {
 	await rm(new URL("prismic.config.json", project));
 	const { exitCode, stderr } = await prismic("init", ["--repo", repo], {