diff --git a/.changeset/old-cycles-add.md b/.changeset/old-cycles-add.md
new file mode 100644
index 00000000..2391fc97
--- /dev/null
+++ b/.changeset/old-cycles-add.md
@@ -0,0 +1,5 @@
+---
+"@inngest/ai": patch
+---
+
+Add Deepseek support
diff --git a/packages/ai/src/env.ts b/packages/ai/src/env.ts
index 2d9ea2e4..14a99572 100644
--- a/packages/ai/src/env.ts
+++ b/packages/ai/src/env.ts
@@ -66,4 +66,5 @@ export enum envKeys {
   OpenAiApiKey = "OPENAI_API_KEY",
   GeminiApiKey = "GEMINI_API_KEY",
   AnthropicApiKey = "ANTHROPIC_API_KEY",
+  DeepSeekApiKey = "DEEPSEEK_API_KEY",
 }
diff --git a/packages/ai/src/models/deepseek.ts b/packages/ai/src/models/deepseek.ts
new file mode 100644
index 00000000..f2ba5b97
--- /dev/null
+++ b/packages/ai/src/models/deepseek.ts
@@ -0,0 +1,72 @@
+import { type AiAdapter } from "../adapter.js";
+import { type OpenAiAiAdapter } from "../adapters/openai.js";
+import { envKeys, processEnv } from "../env";
+
+/**
+ * Create a DeepSeek model using the OpenAI-compatible chat format.
+ * 
+ * By default it targets the `https://api.deepseek.com/v1/` base URL.
+ */
+export const deepseek: AiAdapter.ModelCreator<
+  [options: DeepSeek.AiModelOptions],
+  DeepSeek.AiModel
+> = (options) => {
+  const authKey = options.apiKey || processEnv(envKeys.DeepSeekApiKey) || "";
+
+  // Ensure we add a trailing slash to our base URL if it doesn't have one,
+  // otherwise we'll replace the path instead of appending it.
+  let baseUrl = options.baseUrl || "https://api.deepseek.com/v1/";
+  if (!baseUrl.endsWith("/")) {
+    baseUrl += "/";
+  }
+
+  const url = new URL("chat/completions", baseUrl);
+
+  return {
+    url: url.href,
+    authKey,
+    format: "openai-chat",
+    onCall(_, body) {
+      body.model ||= options.model;
+    },
+    options,
+  } as DeepSeek.AiModel;
+};
+
+export namespace DeepSeek {
+  /**
+   * IDs of models available in the DeepSeek API.
+   */
+  export type Model = "deepseek-chat" | "deepseek-reasoner" | (string & {});
+
+  /**
+   * Options for creating a DeepSeek model.
+   */
+  export interface AiModelOptions {
+    /**
+     * ID of the model to use. Currently supports 'deepseek-chat' (DeepSeek-V3) 
+     * and 'deepseek-reasoner' (DeepSeek-R1).
+     */
+    model: Model;
+
+    /**
+     * The DeepSeek API key to use for authenticating your request. By default we'll
+     * search for and use the `DEEPSEEK_API_KEY` environment variable.
+     */
+    apiKey?: string;
+
+    /**
+     * The base URL for the DeepSeek API.
+     *
+     * @default "https://api.deepseek.com/v1/"
+     */
+    baseUrl?: string;
+  }
+
+  /**
+   * A DeepSeek model using the OpenAI-compatible format for I/O.
+   */
+  export interface AiModel extends OpenAiAiAdapter {
+    options: AiModelOptions;
+  }
+} 
diff --git a/packages/ai/src/models/index.ts b/packages/ai/src/models/index.ts
index e75e764f..af0f5fa3 100644
--- a/packages/ai/src/models/index.ts
+++ b/packages/ai/src/models/index.ts
@@ -1,3 +1,4 @@
-export * from "./anthropic";
-export * from "./gemini";
-export * from "./openai";
+export * from "./anthropic.js";
+export * from "./gemini.js";
+export * from "./openai.js";
+export * from "./deepseek.js";