/topic

Sets the topic shown at the top of the channel.

Where you type it

In the Slack message box.

Add

The new topic.

Example

/topic Launch week: questions here, decisions in the doc

A few built-in commands (like /archive, /rename, /remove) can be limited to owners and admins. A real command built into Slack, checked against its own help pages in November 2026. Official help page