diff --git a/KNOWLEDGE_BASE.md b/KNOWLEDGE_BASE.md
index 72c72054d..04f744e6b 100644
--- a/KNOWLEDGE_BASE.md
+++ b/KNOWLEDGE_BASE.md
@@ -439,6 +439,7 @@ A signed request sees what the web shows you, such as your own pending commits.
 - commit, reply, and quote, and delete your commits;
 - follow or unfollow, mute or unmute, and block or unblock, and list who you muted and blocked;
 - star or unstar, and save or unsave;
+- vote on polls;
 - switch Pastéis mode and give pastéis;
 - report commits;
 - sync from GitHub and save your lane color;
diff --git a/app/Http/Controllers/Api/CommitPollVoteController.php b/app/Http/Controllers/Api/CommitPollVoteController.php
new file mode 100644
index 000000000..ed4e912a1
--- /dev/null
+++ b/app/Http/Controllers/Api/CommitPollVoteController.php
@@ -0,0 +1,27 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Controllers\Api;
+
+use App\Actions\CreateCommitPollVote;
+use App\Http\Requests\CreateApiCommitPollVoteRequest;
+use App\Http\Resources\CommitResource;
+use App\Models\Commit;
+use App\Models\User;
+use App\Queries\CommitPageQuery;
+use Illuminate\Container\Attributes\CurrentUser;
+
+final readonly class CommitPollVoteController
+{
+    /**
+     * Votes on the commit's poll, as the web's Vote button does. It answers with the commit as its page shows it, so
+     * the app gets the poll with its results, which show once the user voted.
+     */
+    public function store(CreateApiCommitPollVoteRequest $request, #[CurrentUser] User $user, Commit $commit, CreateCommitPollVote $action, CommitPageQuery $page): CommitResource
+    {
+        $action->handle($user, $request->option());
+
+        return CommitResource::make($page->get($commit, $user));
+    }
+}
diff --git a/app/Http/Requests/CreateApiCommitPollVoteRequest.php b/app/Http/Requests/CreateApiCommitPollVoteRequest.php
new file mode 100644
index 000000000..6ae6055f2
--- /dev/null
+++ b/app/Http/Requests/CreateApiCommitPollVoteRequest.php
@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Http\Requests;
+
+use App\Models\Commit;
+use App\Models\PollOption;
+use App\Models\User;
+use App\Rules\OpenPoll;
+use Illuminate\Auth\Access\Response;
+use Illuminate\Contracts\Validation\ValidationRule;
+use Illuminate\Foundation\Http\FormRequest;
+use Illuminate\Validation\Rule;
+use Illuminate\Validation\Rules\Exists;
+
+final class CreateApiCommitPollVoteRequest extends FormRequest
+{
+    /**
+     * Like on the web, the user may vote on the poll of any commit they may see. One they may not see looks like it does
+     * not exist.
+     */
+    public function authorize(): Response
+    {
+        return $this->commit()->isVisibleTo($this->voter()) ? Response::allow() : Response::denyAsNotFound();
+    }
+
+    /**
+     * Votes are final, and the author sees the results instead of voting, as on the web (see OpenPoll).
+     *
+     * @return array<string, array<int, string|Exists|ValidationRule>>
+     */
+    public function rules(): array
+    {
+        return [
+            'option' => [
+                'required',
+                'uuid',
+                Rule::exists(PollOption::class, 'id')->where('poll_id', $this->commit()->poll?->id),
+                new OpenPoll($this->commit(), $this->voter()),
+            ],
+        ];
+    }
+
+    public function option(): PollOption
+    {
+        return PollOption::query()->findOrFail($this->string('option')->value());
+    }
+
+    private function commit(): Commit
+    {
+        $commit = $this->route('commit');
+        assert($commit instanceof Commit);
+
+        return $commit;
+    }
+
+    private function voter(): User
+    {
+        $user = $this->user();
+        assert($user instanceof User);
+
+        return $user;
+    }
+}
diff --git a/routes/api.php b/routes/api.php
index 2f2af37d8..1023335bc 100644
--- a/routes/api.php
+++ b/routes/api.php
@@ -5,6 +5,7 @@
 use App\Exceptions\ApiException;
 use App\Http\Controllers\Api\CommitController as ApiCommitController;
 use App\Http\Controllers\Api\CommitPastelController;
+use App\Http\Controllers\Api\CommitPollVoteController;
 use App\Http\Controllers\Api\CommitReplyController;
 use App\Http\Controllers\Api\CommitReportController;
 use App\Http\Controllers\Api\CommitStarController;
@@ -105,6 +106,9 @@
             ->middleware('throttle:60,1')
             ->name('api-commit-pastel.store');
 
+        // Commit Poll Vote...
+        Route::post('commits/{commit}/poll/votes', [CommitPollVoteController::class, 'store'])->name('api-commit-poll-vote.store');
+
         // Private starred commits...
         Route::get('starred', [StarredCommitController::class, 'index'])->name('api-starred.index');
 
diff --git a/tests/Feature/Controllers/Api/CommitPollVoteControllerTest.php b/tests/Feature/Controllers/Api/CommitPollVoteControllerTest.php
new file mode 100644
index 000000000..7a44d5f59
--- /dev/null
+++ b/tests/Feature/Controllers/Api/CommitPollVoteControllerTest.php
@@ -0,0 +1,141 @@
+<?php
+
+declare(strict_types=1);
+
+use App\Models\Commit;
+use App\Models\Poll;
+use App\Models\PollVote;
+use App\Models\User;
+
+beforeEach(function (): void {
+    $this->user = User::factory()->create();
+    $this->keyPair = apiKeyPairFor($this->user);
+});
+
+it('votes and answers with the commit, whose poll now shows the results', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+    PollVote::factory()->for($poll->options[0], 'option')->count(2)->create();
+
+    $response = signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[1]->id]);
+
+    $response->assertOk()
+        ->assertJsonPath('data.id', $poll->commit_id)
+        ->assertJsonPath('data.poll.has_voted', true)
+        ->assertJsonPath('data.poll.total_votes', 3)
+        ->assertJsonPath('data.poll.options.0.votes_count', 2)
+        ->assertJsonPath('data.poll.options.0.voted', false)
+        ->assertJsonPath('data.poll.options.0.percentage', 67)
+        ->assertJsonPath('data.poll.options.1.votes_count', 1)
+        ->assertJsonPath('data.poll.options.1.voted', true)
+        ->assertJsonPath('data.poll.options.1.percentage', 33);
+
+    expect($this->user->pollVotes()->sole()->poll_option_id)->toBe($poll->options[1]->id);
+});
+
+it('answers with the commit as the commit endpoint shows it', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+
+    $response = signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id]);
+
+    $response->assertOk()
+        ->assertExactJson(['data' => signedApiRequest($this->keyPair, 'GET', route('api-commit.show', $poll->commit))->json('data')]);
+});
+
+it('requires an option of the poll', function (Closure $option, string $message): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $option()])
+        ->assertUnprocessable()
+        ->assertJsonValidationErrors(['option' => $message]);
+
+    expect(PollVote::query()->exists())->toBeFalse();
+})->with([
+    'missing' => [fn (): null => null, 'The option field is required.'],
+    'not a uuid' => [fn (): string => 'tabs', 'The option field must be a valid UUID.'],
+    'of another poll' => [fn (): string => Poll::factory()->withOptions('Vim', 'Emacs')->create()->options[0]->id, 'The selected option is invalid.'],
+]);
+
+it('may not vote on a commit without a poll', function (): void {
+    $commit = Commit::factory()->create();
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $commit), ['option' => Poll::factory()->withOptions('Vim', 'Emacs')->create()->options[0]->id])
+        ->assertUnprocessable()
+        ->assertJsonValidationErrors(['option' => 'The selected option is invalid.']);
+});
+
+it('explains why a vote is refused, as the web does', function (Closure $poll, string $message): void {
+    $poll = $poll($this->user);
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id])
+        ->assertUnprocessable()
+        ->assertJsonValidationErrors(['option' => $message]);
+
+    expect(PollVote::query()->exists())->toBeFalse();
+})->with([
+    'own poll' => [fn (User $user): Poll => Poll::factory()->for(Commit::factory()->for($user))->withOptions('Tabs', 'Spaces')->create(), "You can't vote on your own poll."],
+    'own pending poll' => [fn (User $user): Poll => Poll::factory()->for(Commit::factory()->for($user)->pending())->withOptions('Tabs', 'Spaces')->unopened()->create(), 'This poll is not open for votes.'],
+    'unopened poll' => [fn (User $user): Poll => Poll::factory()->withOptions('Tabs', 'Spaces')->unopened()->create(), 'This poll is not open for votes.'],
+    'closed poll' => [fn (User $user): Poll => Poll::factory()->withOptions('Tabs', 'Spaces')->closed()->create(), 'This poll has closed.'],
+]);
+
+it('refuses a second vote, since votes are final', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+    PollVote::factory()->for($poll->options[0], 'option')->for($this->user)->create();
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[1]->id])
+        ->assertUnprocessable()
+        ->assertJsonValidationErrors(['option' => 'You have already voted on this poll.']);
+
+    expect($this->user->pollVotes()->sole()->poll_option_id)->toBe($poll->options[0]->id);
+});
+
+it('may not vote on a poll the user may not see', function (string $state): void {
+    $poll = Poll::factory()->for(Commit::factory()->{$state}())->withOptions('Tabs', 'Spaces')->create();
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id])
+        ->assertNotFound()
+        ->assertDontSee($poll->commit->body);
+
+    expect(PollVote::query()->exists())->toBeFalse();
+})->with(['pending', 'rejected']);
+
+it('may not vote across a block in either direction', function (bool $voterBlocks): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+    $author = $poll->commit->user;
+
+    $voterBlocks ? $this->user->blocking()->attach($author) : $author->blocking()->attach($this->user);
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id])
+        ->assertNotFound();
+
+    expect(PollVote::query()->exists())->toBeFalse();
+})->with([true, false]);
+
+it('may still vote across a mute, as on the web', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+    $this->user->muting()->attach($poll->commit->user);
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id])
+        ->assertOk()
+        ->assertJsonPath('data.poll.has_voted', true);
+});
+
+it('may not vote on a deleted or unknown commit', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+    $poll->commit->delete();
+
+    signedApiRequest($this->keyPair, 'POST', route('api-commit-poll-vote.store', $poll->commit_id), ['option' => $poll->options[0]->id])
+        ->assertNotFound();
+
+    signedApiRequest($this->keyPair, 'POST', 'api/v1/commits/0199e3a4-0000-7000-8000-000000000000/poll/votes', ['option' => $poll->options[0]->id])
+        ->assertNotFound();
+});
+
+it('requires a signed request', function (): void {
+    $poll = Poll::factory()->withOptions('Tabs', 'Spaces')->create();
+
+    $this->postJson(route('api-commit-poll-vote.store', $poll->commit), ['option' => $poll->options[0]->id])
+        ->assertUnauthorized();
+
+    expect(PollVote::query()->exists())->toBeFalse();
+});