diff --git a/src/operations/client_bulk_write/executor.ts b/src/operations/client_bulk_write/executor.ts
index 93acaac2160..7475fcdab20 100644
--- a/src/operations/client_bulk_write/executor.ts
+++ b/src/operations/client_bulk_write/executor.ts
@@ -2,6 +2,7 @@ import { ClientBulkWriteCursor } from '../../cursor/client_bulk_write_cursor';
 import {
   MongoClientBulkWriteError,
   MongoClientBulkWriteExecutionError,
+  MongoInvalidArgumentError,
   MongoServerError
 } from '../../error';
 import { type MongoClient } from '../../mongo_client';
@@ -53,6 +54,20 @@ export class ClientBulkWriteExecutor {
     if (!this.options.writeConcern) {
       this.options.writeConcern = WriteConcern.fromOptions(this.client.options);
     }
+
+    if (this.options.writeConcern?.w === 0) {
+      if (this.options.verboseResults) {
+        throw new MongoInvalidArgumentError(
+          'Cannot request unacknowledged write concern and verbose results'
+        );
+      }
+
+      if (this.options.ordered) {
+        throw new MongoInvalidArgumentError(
+          'Cannot request unacknowledged write concern and ordered writes'
+        );
+      }
+    }
   }
 
   /**
diff --git a/test/integration/crud/crud.prose.test.ts b/test/integration/crud/crud.prose.test.ts
index de48cbbaca8..6722bf605c9 100644
--- a/test/integration/crud/crud.prose.test.ts
+++ b/test/integration/crud/crud.prose.test.ts
@@ -738,7 +738,8 @@ describe('CRUD Prose Spec Tests', () => {
         async test() {
           const error = await client
             .bulkWrite([{ name: 'insertOne', namespace: 'db.coll', document: document }], {
-              writeConcern: { w: 0 }
+              writeConcern: { w: 0 },
+              ordered: false
             })
             .catch(error => error);
           expect(error.message).to.include('Client bulk write operation ops of length');
@@ -763,7 +764,7 @@ describe('CRUD Prose Spec Tests', () => {
           const error = await client
             .bulkWrite(
               [{ name: 'replaceOne', namespace: 'db.coll', filter: {}, replacement: document }],
-              { writeConcern: { w: 0 } }
+              { writeConcern: { w: 0 }, ordered: false }
             )
             .catch(error => error);
           expect(error.message).to.include('Client bulk write operation ops of length');
@@ -1079,4 +1080,85 @@ describe('CRUD Prose Spec Tests', () => {
       expect(command).to.have.property('maxTimeMS', 2000);
     });
   });
+
+  describe('15. `MongoClient.bulkWrite` with unacknowledged write concern uses `w:0` for all batches', function () {
+    // This test must only be run on 8.0+ servers. This test must be skipped on Atlas Serverless.
+    // If testing with a sharded cluster, only connect to one mongos. This is intended to ensure the `countDocuments` operation
+    // uses the same connection as the `bulkWrite` to get the correct connection count. (See
+    // [DRIVERS-2921](https://jira.mongodb.org/browse/DRIVERS-2921)).
+    // Construct a `MongoClient` (referred to as `client`) with
+    // [command monitoring](../../command-logging-and-monitoring/command-logging-and-monitoring.md) enabled to observe
+    // CommandStartedEvents. Perform a `hello` command using `client` and record the `maxBsonObjectSize` and
+    // `maxMessageSizeBytes` values in the response.
+    // Construct a `MongoCollection` (referred to as `coll`) for the collection "db.coll". Drop `coll`.
+    // Use the `create` command to create "db.coll" to workaround [SERVER-95537](https://jira.mongodb.org/browse/SERVER-95537).
+    // Construct the following write model (referred to as `model`):
+    // InsertOne: {
+    //   "namespace": "db.coll",
+    //   "document": { "a": "b".repeat(maxBsonObjectSize - 500) }
+    // }
+    // Construct a list of write models (referred to as `models`) with `model` repeated
+    // `maxMessageSizeBytes / maxBsonObjectSize + 1` times.
+    // Call `client.bulkWrite` with `models`. Pass `BulkWriteOptions` with `ordered` set to `false` and `writeConcern` set to
+    // an unacknowledged write concern. Assert no error occurred. Assert the result indicates the write was unacknowledged.
+    // Assert that two CommandStartedEvents (referred to as `firstEvent` and `secondEvent`) were observed for the `bulkWrite`
+    // command. Assert that the length of `firstEvent.command.ops` is `maxMessageSizeBytes / maxBsonObjectSize`. Assert that
+    // the length of `secondEvent.command.ops` is 1. If the driver exposes `operationId`s in its CommandStartedEvents, assert
+    // that `firstEvent.operationId` is equal to `secondEvent.operationId`. Assert both commands include
+    // `writeConcern: {w: 0}`.
+    // To force completion of the `w:0` writes, execute `coll.countDocuments` and expect the returned count is
+    // `maxMessageSizeBytes / maxBsonObjectSize + 1`. This is intended to avoid incomplete writes interfering with other tests
+    // that may use this collection.
+    let client: MongoClient;
+    let maxBsonObjectSize;
+    let maxMessageSizeBytes;
+    let numModels;
+    const models: AnyClientBulkWriteModel[] = [];
+    const commands: CommandStartedEvent[] = [];
+
+    beforeEach(async function () {
+      const uri = this.configuration.url({
+        useMultipleMongoses: false
+      });
+      client = this.configuration.newClient(uri, { monitorCommands: true });
+      await client.connect();
+      await client.db('db').collection('coll').drop();
+      await client.db('db').createCollection('coll');
+      const hello = await client.db('admin').command({ hello: 1 });
+      maxBsonObjectSize = hello.maxBsonObjectSize;
+      maxMessageSizeBytes = hello.maxMessageSizeBytes;
+      numModels = Math.floor(maxMessageSizeBytes / maxBsonObjectSize) + 1;
+      Array.from({ length: numModels }, () => {
+        models.push({
+          name: 'insertOne',
+          namespace: 'db.coll',
+          document: {
+            a: 'b'.repeat(maxBsonObjectSize - 500)
+          }
+        });
+      });
+
+      client.on('commandStarted', filterForCommands('bulkWrite', commands));
+      commands.length = 0;
+    });
+
+    afterEach(async function () {
+      await client.close();
+    });
+
+    it('performs all writes unacknowledged', {
+      metadata: { requires: { mongodb: '>=8.0.0', serverless: 'forbid' } },
+      async test() {
+        const result = await client.bulkWrite(models, { ordered: false, writeConcern: { w: 0 } });
+        expect(result).to.deep.equal({ ok: 1 });
+        expect(commands.length).to.equal(2);
+        expect(commands[0].command.ops.length).to.equal(numModels - 1);
+        expect(commands[0].command.writeConcern.w).to.equal(0);
+        expect(commands[1].command.ops.length).to.equal(1);
+        expect(commands[1].command.writeConcern.w).to.equal(0);
+        const count = await client.db('db').collection('coll').countDocuments();
+        expect(count).to.equal(3);
+      }
+    });
+  });
 });
diff --git a/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.json b/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.json
index 1099b6a1e9f..61bb00726c0 100644
--- a/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.json
+++ b/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.json
@@ -3,7 +3,8 @@
   "schemaVersion": "1.7",
   "runOnRequirements": [
     {
-      "minServerVersion": "8.0"
+      "minServerVersion": "8.0",
+      "serverless": "forbid"
     }
   ],
   "createEntities": [
@@ -90,7 +91,8 @@
                   }
                 }
               }
-            ]
+            ],
+            "ordered": false
           },
           "expectResult": {
             "insertedCount": {
@@ -157,7 +159,7 @@
                 "command": {
                   "bulkWrite": 1,
                   "errorsOnly": true,
-                  "ordered": true,
+                  "ordered": false,
                   "ops": [
                     {
                       "insert": 0,
diff --git a/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.yml b/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.yml
index fcc6b7b3ec2..2d545259539 100644
--- a/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.yml
+++ b/test/spec/command-logging-and-monitoring/monitoring/unacknowledged-client-bulkWrite.yml
@@ -4,6 +4,7 @@ schemaVersion: "1.7"
 
 runOnRequirements:
   - minServerVersion: "8.0"
+    serverless: forbid
 
 createEntities:
   - client:
@@ -49,6 +50,7 @@ tests:
                 namespace: *namespace
                 filter: { _id: 3 }
                 update: { $set: { x: 333 } }
+          ordered: false
         expectResult:
           insertedCount:
             $$unsetOrMatches: 0
@@ -88,7 +90,7 @@ tests:
               command:
                 bulkWrite: 1
                 errorsOnly: true
-                ordered: true
+                ordered: false
                 ops:
                   - insert: 0
                     document: { _id: 4, x: 44 }
diff --git a/test/spec/crud/unified/client-bulkWrite-errors.json b/test/spec/crud/unified/client-bulkWrite-errors.json
index 8cc45bb5f2d..015bd95c990 100644
--- a/test/spec/crud/unified/client-bulkWrite-errors.json
+++ b/test/spec/crud/unified/client-bulkWrite-errors.json
@@ -450,6 +450,64 @@
           }
         }
       ]
+    },
+    {
+      "description": "Requesting unacknowledged write with verboseResults is a client-side error",
+      "operations": [
+        {
+          "name": "clientBulkWrite",
+          "object": "client0",
+          "arguments": {
+            "models": [
+              {
+                "insertOne": {
+                  "namespace": "crud-tests.coll0",
+                  "document": {
+                    "_id": 10
+                  }
+                }
+              }
+            ],
+            "verboseResults": true,
+            "ordered": false,
+            "writeConcern": {
+              "w": 0
+            }
+          },
+          "expectError": {
+            "isClientError": true,
+            "errorContains": "Cannot request unacknowledged write concern and verbose results"
+          }
+        }
+      ]
+    },
+    {
+      "description": "Requesting unacknowledged write with ordered is a client-side error",
+      "operations": [
+        {
+          "name": "clientBulkWrite",
+          "object": "client0",
+          "arguments": {
+            "models": [
+              {
+                "insertOne": {
+                  "namespace": "crud-tests.coll0",
+                  "document": {
+                    "_id": 10
+                  }
+                }
+              }
+            ],
+            "writeConcern": {
+              "w": 0
+            }
+          },
+          "expectError": {
+            "isClientError": true,
+            "errorContains": "Cannot request unacknowledged write concern and ordered writes"
+          }
+        }
+      ]
     }
   ]
 }
diff --git a/test/spec/crud/unified/client-bulkWrite-errors.yml b/test/spec/crud/unified/client-bulkWrite-errors.yml
index 6c513006cec..79c04961615 100644
--- a/test/spec/crud/unified/client-bulkWrite-errors.yml
+++ b/test/spec/crud/unified/client-bulkWrite-errors.yml
@@ -239,3 +239,32 @@ tests:
           verboseResults: true
         expectError:
           isClientError: true
+  - description: "Requesting unacknowledged write with verboseResults is a client-side error"
+    operations:
+      - name: clientBulkWrite
+        object: *client0
+        arguments:
+          models:
+            - insertOne:
+                namespace: *namespace
+                document: { _id: 10 }
+          verboseResults: true
+          ordered: false
+          writeConcern: { w: 0 }
+        expectError:
+          isClientError: true
+          errorContains: "Cannot request unacknowledged write concern and verbose results"
+  - description: "Requesting unacknowledged write with ordered is a client-side error"
+    operations:
+      - name: clientBulkWrite
+        object: *client0
+        arguments:
+          models:
+            - insertOne:
+                namespace: *namespace
+                document: { _id: 10 }
+          # Omit `ordered` option. Defaults to true.
+          writeConcern: { w: 0 }
+        expectError:
+          isClientError: true
+          errorContains: "Cannot request unacknowledged write concern and ordered writes"