diff --git a/.changeset/fluffy-horses-enjoy.md b/.changeset/fluffy-horses-enjoy.md
new file mode 100644
index 000000000..9ed297817
--- /dev/null
+++ b/.changeset/fluffy-horses-enjoy.md
@@ -0,0 +1,6 @@
+---
+"@osdk/client": patch
+"@osdk/api": patch
+---
+
+Fixes attachment upload inputs sending incorrect in browser contexts
diff --git a/etc/api.report.api.md b/etc/api.report.api.md
index 9552df3ad..91dc8b809 100644
--- a/etc/api.report.api.md
+++ b/etc/api.report.api.md
@@ -204,8 +204,10 @@ export interface Attachment {
     rid: string;
 }
 
-// @public
-export interface AttachmentUpload extends Blob {
+// @public (undocumented)
+export interface AttachmentUpload {
+    // (undocumented)
+    readonly data: Blob;
     // (undocumented)
     readonly name: string;
 }
@@ -243,7 +245,9 @@ export type ConvertProps<FROM extends ObjectOrInterfaceDefinition, TO extends Va
 // @public
 export interface DataValueClientToWire {
     // (undocumented)
-    attachment: string | AttachmentUpload;
+    attachment: string | AttachmentUpload | Blob & {
+        readonly name: string;
+    };
     // (undocumented)
     boolean: boolean;
     // (undocumented)
diff --git a/packages/api/src/mapping/DataValueMapping.ts b/packages/api/src/mapping/DataValueMapping.ts
index 42f47bb63..dcc42b20b 100644
--- a/packages/api/src/mapping/DataValueMapping.ts
+++ b/packages/api/src/mapping/DataValueMapping.ts
@@ -50,7 +50,7 @@ export interface DataValueWireToClient {
  * Map from the DataValue type to the typescript type that we accept
  */
 export interface DataValueClientToWire {
-  attachment: string | AttachmentUpload;
+  attachment: string | AttachmentUpload | Blob & { readonly name: string };
   boolean: boolean;
   byte: number;
   datetime: string;
diff --git a/packages/api/src/mapping/PropertyValueMapping.ts b/packages/api/src/mapping/PropertyValueMapping.ts
index c35bb5185..35f973116 100644
--- a/packages/api/src/mapping/PropertyValueMapping.ts
+++ b/packages/api/src/mapping/PropertyValueMapping.ts
@@ -59,7 +59,7 @@ export type GetClientPropertyValueFromWire<
  * Map from the PropertyDefinition type to the typescript type that we accept
  */
 export interface PropertyValueClientToWire {
-  attachment: string | AttachmentUpload;
+  attachment: string | AttachmentUpload | Blob & { readonly name: string };
   boolean: boolean;
   byte: number;
   datetime: string;
diff --git a/packages/api/src/object/Attachment.ts b/packages/api/src/object/Attachment.ts
index 78f56e0e9..c39312b09 100644
--- a/packages/api/src/object/Attachment.ts
+++ b/packages/api/src/object/Attachment.ts
@@ -25,12 +25,10 @@ export interface Attachment {
    */
   fetchContents(): Promise<Response>;
 }
-/**
- * This interface should also accept the File object from
- * the W3C FileApi https://www.w3.org/TR/FileAPI/#file-section
- */
-export interface AttachmentUpload extends Blob {
+
+export interface AttachmentUpload {
   readonly name: string;
+  readonly data: Blob;
 }
 
 export interface AttachmentMetadata {
diff --git a/packages/client/src/actions/actions.test.ts b/packages/client/src/actions/actions.test.ts
index a01f37e9c..d4bf51416 100644
--- a/packages/client/src/actions/actions.test.ts
+++ b/packages/client/src/actions/actions.test.ts
@@ -217,10 +217,24 @@ describe("actions", () => {
       typeof clientBoundBatchActionTakesAttachment
     >[0];
 
-    expectTypeOf<{ attachment: string | AttachmentUpload }>().toMatchTypeOf<
+    expectTypeOf<
+      {
+        attachment:
+          | string
+          | AttachmentUpload
+          | Blob & { readonly name: string };
+      }
+    >().toMatchTypeOf<
       InferredParamType
     >();
-    expectTypeOf<{ attachment: string | AttachmentUpload }[]>().toMatchTypeOf<
+    expectTypeOf<
+      {
+        attachment:
+          | string
+          | AttachmentUpload
+          | Blob & { readonly name: string };
+      }[]
+    >().toMatchTypeOf<
       InferredBatchParamType
     >();
 
@@ -228,12 +242,23 @@ describe("actions", () => {
       stubData.attachmentUploadRequestBody[stubData.localAttachment1.filename];
 
     const attachment = createAttachmentUpload(blob, "file1.txt");
+
+    // Mimics the Web file API (https://developer.mozilla.org/en-US/docs/Web/API/File). The File constructor is only available in Node 19.2.0 and above
+    const fileAttachment = Object.assign(blob, { name: "file1.txt" });
+
     const result = await client(actionTakesAttachment).applyAction({
       attachment,
     });
 
+    const result2 = await client(actionTakesAttachment).applyAction({
+      attachment: fileAttachment,
+    });
+
     expectTypeOf<typeof result>().toEqualTypeOf<undefined>();
     expect(result).toBeUndefined();
+
+    expectTypeOf<typeof result2>().toEqualTypeOf<undefined>();
+    expect(result2).toBeUndefined();
   });
   it("conditionally returns edits in batch mode", async () => {
     const result = await client(moveOffice).batchApplyAction([
diff --git a/packages/client/src/object/AttachmentUpload.ts b/packages/client/src/object/AttachmentUpload.ts
index 50b778146..9fb4f1a5d 100644
--- a/packages/client/src/object/AttachmentUpload.ts
+++ b/packages/client/src/object/AttachmentUpload.ts
@@ -17,18 +17,13 @@
 import type { AttachmentUpload } from "@osdk/api";
 
 export function isAttachmentUpload(o: any): o is AttachmentUpload {
-  return o instanceof Blob && "name" in o;
+  return typeof o === `object` && "name" in o && "data" in o
+    && o.data instanceof Blob;
 }
 
 export function createAttachmentUpload(
   data: Blob,
   name: string,
 ): AttachmentUpload {
-  const attachmentUpload = Object.create(data, {
-    name: { value: name },
-    size: { value: data.size },
-    type: { value: data.type },
-  });
-
-  return attachmentUpload as AttachmentUpload;
+  return { data, name };
 }
diff --git a/packages/client/src/util/toDataValue.test.ts b/packages/client/src/util/toDataValue.test.ts
index b2b775bd7..d913315d0 100644
--- a/packages/client/src/util/toDataValue.test.ts
+++ b/packages/client/src/util/toDataValue.test.ts
@@ -141,7 +141,7 @@ describe(toDataValue, () => {
     expect(definitionConversion).toMatchInlineSnapshot(expected);
   });
 
-  it("converts attachment uploads correctly", async () => {
+  it("converts blob attachment uploads correctly", async () => {
     const blob =
       stubData.attachmentUploadRequestBody[stubData.localAttachment1.filename];
     const attachmentUpload = createAttachmentUpload(blob, "file1.txt");
@@ -151,4 +151,18 @@ describe(toDataValue, () => {
       "ri.attachments.main.attachment.86016861-707f-4292-b258-6a7108915a75",
     );
   });
+
+  it("converts file attachment uploads correctly", async () => {
+    // Mimics the Web file API (https://developer.mozilla.org/en-US/docs/Web/API/File). The File constructor is only available in Node 19.2.0 and above
+    const file = Object.assign(
+      stubData.attachmentUploadRequestBody[stubData.localAttachment1.filename],
+      { name: "file1.txt" },
+    );
+
+    const converted = await toDataValue(file, clientCtx);
+
+    expect(converted).toEqual(
+      "ri.attachments.main.attachment.86016861-707f-4292-b258-6a7108915a75",
+    );
+  });
 });
diff --git a/packages/client/src/util/toDataValue.ts b/packages/client/src/util/toDataValue.ts
index 84f9145cd..b2e2d6402 100644
--- a/packages/client/src/util/toDataValue.ts
+++ b/packages/client/src/util/toDataValue.ts
@@ -51,7 +51,7 @@ export async function toDataValue(
   if (isAttachmentUpload(value)) {
     const attachment = await OntologiesV2.Attachments.upload(
       client,
-      value,
+      value.data,
       {
         filename: value.name,
       },
@@ -59,6 +59,17 @@ export async function toDataValue(
     return await toDataValue(attachment.rid, client);
   }
 
+  if (typeof value === "object" && value instanceof Blob && "name" in value) {
+    const attachment = await OntologiesV2.Attachments.upload(
+      client,
+      value,
+      {
+        filename: value.name as string,
+      },
+    );
+    return await toDataValue(attachment.rid, client);
+  }
+
   // objects just send the JSON'd primaryKey
   if (isOntologyObjectV2(value)) {
     return await toDataValue(value.__primaryKey, client);
diff --git a/packages/client/src/util/toDataValueQueries.ts b/packages/client/src/util/toDataValueQueries.ts
index ae8b4ada7..85a64c71d 100644
--- a/packages/client/src/util/toDataValueQueries.ts
+++ b/packages/client/src/util/toDataValueQueries.ts
@@ -52,7 +52,7 @@ export async function toDataValueQueries(
       if (isAttachmentUpload(value)) {
         const attachment = await OntologiesV2.Attachments.upload(
           client,
-          value,
+          value.data,
           {
             filename: value.name,
           },
@@ -60,6 +60,19 @@ export async function toDataValueQueries(
         return attachment.rid;
       }
 
+      if (
+        typeof value === "object" && value instanceof Blob && "name" in value
+      ) {
+        const attachment = await OntologiesV2.Attachments.upload(
+          client,
+          value,
+          {
+            filename: value.name as string,
+          },
+        );
+        return attachment.rid;
+      }
+
       // If it's not an upload, it's just an attachment rid string which we can pass through
       return value;
     }
diff --git a/packages/example-generator/src/check.test.ts b/packages/example-generator/src/check.test.ts
index 339baf313..2cd765269 100644
--- a/packages/example-generator/src/check.test.ts
+++ b/packages/example-generator/src/check.test.ts
@@ -21,9 +21,13 @@ import { run } from "./run.js";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-it("Generates code that matches the files on disk in the examples dir", async () => {
-  await run({
-    outputDirectory: path.join(__dirname, "..", "..", "..", "examples"),
-    check: true,
-  });
-});
+it(
+  "Generates code that matches the files on disk in the examples dir",
+  async () => {
+    await run({
+      outputDirectory: path.join(__dirname, "..", "..", "..", "examples"),
+      check: true,
+    });
+  },
+  { timeout: 15000 },
+);