diff --git a/internal/commands/comment.go b/internal/commands/comment.go
index 7b7a33b2..530c3275 100644
--- a/internal/commands/comment.go
+++ b/internal/commands/comment.go
@@ -298,6 +298,9 @@ Comma-separated IDs add the same comment to multiple items:
   basecamp comment 789,012,345 "Looks good!"
   basecamp comment https://3.basecamp.com/123/buckets/456/todos/789 "Looks good!"
 
+Content can also be piped from stdin:
+  printf 'Looks good!' | basecamp comment 789
+
 Content supports Markdown and @mentions (@Name or @First.Last):
   basecamp comment 789 "Hey @Jane.Smith, **please review**"`,
 		Annotations: map[string]string{"agent_notes": "Comments are flat — reply to parent item, not to other comments\nURL fragments (#__recording_456) are comment IDs — comment on the parent recording_id, not the comment_id\nComments are on items (todos, messages, cards, etc.) — not on other comments"},
@@ -331,6 +334,13 @@ Content supports Markdown and @mentions (@Name or @First.Last):
 				}
 			}
 
+			if !edit && strings.TrimSpace(content) == "" {
+				stdinContent, hasPipedStdin := readPipedStdin()
+				if hasPipedStdin {
+					content = stdinContent
+				}
+			}
+
 			// Show help when invoked with no content; keep error if editor was opened
 			if strings.TrimSpace(content) == "" {
 				if edit {
diff --git a/internal/commands/comment_test.go b/internal/commands/comment_test.go
index 963c26de..d83a4bca 100644
--- a/internal/commands/comment_test.go
+++ b/internal/commands/comment_test.go
@@ -1,6 +1,12 @@
 package commands
 
 import (
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"os"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -56,3 +62,153 @@ func TestCommentsGroupAcceptsInFlag(t *testing.T) {
 	assert.NotContains(t, err.Error(), "unknown flag")
 	assert.NotContains(t, err.Error(), "unknown shorthand")
 }
+
+type mockCommentCreateTransport struct {
+	capturedBody []byte
+}
+
+func (t *mockCommentCreateTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	header := make(http.Header)
+	header.Set("Content-Type", "application/json")
+
+	if req.Method != http.MethodPost {
+		return nil, errors.New("unexpected request")
+	}
+	if !strings.HasSuffix(req.URL.Path, "/comments.json") {
+		return nil, errors.New("unexpected path: " + req.URL.Path)
+	}
+
+	if req.Body != nil {
+		body, _ := io.ReadAll(req.Body)
+		t.capturedBody = body
+		req.Body.Close()
+	}
+
+	return &http.Response{
+		StatusCode: 201,
+		Body:       io.NopCloser(strings.NewReader(`{"id": 999, "content": "<p>hello from stdin</p>", "status": "active"}`)),
+		Header:     header,
+	}, nil
+}
+
+func TestCommentCreateReadsContentFromStdin(t *testing.T) {
+	transport := &mockCommentCreateTransport{}
+	app, _ := newTestAppWithTransport(t, transport)
+
+	r, w, err := os.Pipe()
+	require.NoError(t, err)
+	_, err = io.WriteString(w, "hello from stdin")
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	origStdin := os.Stdin
+	os.Stdin = r
+	t.Cleanup(func() {
+		os.Stdin = origStdin
+		r.Close()
+	})
+
+	cmd := NewCommentCmd()
+	err = executeCommand(cmd, app, "123")
+	require.NoError(t, err)
+	require.NotEmpty(t, transport.capturedBody)
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(transport.capturedBody, &body))
+	assert.Equal(t, "<p>hello from stdin</p>", body["content"])
+}
+
+func TestCommentCreatePrefersPositionalContentOverStdin(t *testing.T) {
+	transport := &mockCommentCreateTransport{}
+	app, _ := newTestAppWithTransport(t, transport)
+
+	r, w, err := os.Pipe()
+	require.NoError(t, err)
+	_, err = io.WriteString(w, "ignored stdin")
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	origStdin := os.Stdin
+	os.Stdin = r
+	t.Cleanup(func() {
+		os.Stdin = origStdin
+		r.Close()
+	})
+
+	cmd := NewCommentCmd()
+	err = executeCommand(cmd, app, "123", "hello from args")
+	require.NoError(t, err)
+	require.NotEmpty(t, transport.capturedBody)
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(transport.capturedBody, &body))
+	assert.Equal(t, "<p>hello from args</p>", body["content"])
+}
+
+func TestCommentsCreateReadsContentFromStdin(t *testing.T) {
+	transport := &mockCommentCreateTransport{}
+	app, _ := newTestAppWithTransport(t, transport)
+
+	r, w, err := os.Pipe()
+	require.NoError(t, err)
+	_, err = io.WriteString(w, "hello from stdin")
+	require.NoError(t, err)
+	require.NoError(t, w.Close())
+
+	origStdin := os.Stdin
+	os.Stdin = r
+	t.Cleanup(func() {
+		os.Stdin = origStdin
+		r.Close()
+	})
+
+	cmd := NewCommentsCmd()
+	err = executeCommand(cmd, app, "create", "123")
+	require.NoError(t, err)
+	require.NotEmpty(t, transport.capturedBody)
+
+	var body map[string]any
+	require.NoError(t, json.Unmarshal(transport.capturedBody, &body))
+	assert.Equal(t, "<p>hello from stdin</p>", body["content"])
+}
+
+func TestCommentCreateMissingContentReturnsUsageBeforeAccountResolution(t *testing.T) {
+	app, _ := setupTestApp(t)
+	app.Config.AccountID = ""
+	app.Flags.JSON = true
+
+	devNull, err := os.Open(os.DevNull)
+	if err != nil {
+		t.Skip("dev null not available")
+	}
+
+	origStdin := os.Stdin
+	os.Stdin = devNull
+	t.Cleanup(func() {
+		os.Stdin = origStdin
+		devNull.Close()
+	})
+
+	cmd := NewCommentCmd()
+	err = executeCommand(cmd, app, "123")
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "<content> required")
+	assert.NotContains(t, err.Error(), "account")
+}
+
+func TestReadPipedStdinIgnoresUnreadableStdin(t *testing.T) {
+	r, w, err := os.Pipe()
+	require.NoError(t, err)
+	require.NoError(t, r.Close())
+	require.NoError(t, w.Close())
+
+	origStdin := os.Stdin
+	os.Stdin = r
+	t.Cleanup(func() {
+		os.Stdin = origStdin
+	})
+
+	content, hasPipedStdin := readPipedStdin()
+	assert.Empty(t, content)
+	assert.False(t, hasPipedStdin)
+}
diff --git a/internal/commands/helpers.go b/internal/commands/helpers.go
index d355f870..4c873db2 100644
--- a/internal/commands/helpers.go
+++ b/internal/commands/helpers.go
@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"os"
 	"strconv"
 	"strings"
@@ -79,6 +80,22 @@ func isMachineOutput(cmd *cobra.Command) bool {
 	return false
 }
 
+func readPipedStdin() (string, bool) {
+	fi, err := os.Stdin.Stat()
+	if err != nil {
+		return "", false
+	}
+	if (fi.Mode() & os.ModeCharDevice) != 0 {
+		return "", false
+	}
+
+	data, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		return "", false
+	}
+	return string(data), true
+}
+
 // DockTool represents a tool in a project's dock.
 type DockTool struct {
 	Name    string `json:"name"`