Slack Shared Channels

A shared channel is a Slack channel that two or more separate organizations use simultaneously. Both teams post into the same conversation, see the same history, and share files — each from their own Slack workspace. Shared channels are the foundation of Slack Connect and the most efficient way to collaborate with external partners over time.

What Makes a Channel "Shared"

NORMAL CHANNEL                SHARED CHANNEL
──────────────────────────    ──────────────────────────────────────
Members from one workspace    Members from two or more workspaces
Owned by one workspace        Co-owned by multiple workspaces
No cross-company messaging    Cross-company messaging in real time
One set of workspace rules    Rules from BOTH workspaces apply

A small icon — a handshake or link symbol — appears next to shared channel names in the sidebar to distinguish them from internal channels.

How to Create a Shared Channel

Step 1: Create the Channel on Your Side

1. Create a new channel (e.g., #ext-partner-globaltech).
2. Add your internal team members who need to collaborate with the partner.

Step 2: Send a Slack Connect Invitation

1. Inside the channel, click the channel name in the header.
2. Select "Add people" or "Share via Slack Connect".
3. Enter the external contact's email address.
4. Slack sends them an invitation.

Step 3: External Partner Accepts

1. The external partner's Slack admin receives the invitation.
2. Their admin reviews and approves the connection.
3. The channel becomes shared — it appears in both workspaces simultaneously.

APPROVAL FLOW

  You send invite →
  Partner's admin receives it →
  Partner admin approves →
  Channel becomes shared ✓

  Timeline: Usually within hours (depends on their admin)

Channel Naming Convention for Shared Channels

Both workspaces can name the channel differently on their own side. Use a clear external prefix on your side:

YOUR WORKSPACE NAME     THEIR WORKSPACE NAME
────────────────────    ────────────────────
#ext-globaltech         #slack-acmecorp
#ext-agency-xyz         #client-acme

You control your naming; they control theirs.
Both sides see the same messages.

Visibility Controls

When you set up the shared channel, you choose whether it is public or private on your side. A shared channel that is public in your workspace means any of your members can browse and join it. A private shared channel requires an invitation even on your own side.

SHARED CHANNEL VISIBILITY SETTINGS

  YOUR WORKSPACE     THEIR WORKSPACE    RESULT
  ────────────────   ─────────────────  ────────────────────────
  Public             Public             Both sides open
  Public             Private            Your side open; their side invite-only
  Private            Private            Both sides invite-only (most secure)

Moderation in Shared Channels

Both workspace admins can see the shared channel. Either side can remove the connection at any time, which ends the bridge and makes the channel private to that workspace again. Messages posted before the disconnection remain visible to each side's own members.

Channel managers on each side can also pin messages, set the channel topic, and moderate content in the shared space.

What Happens When You Disconnect a Shared Channel

BEFORE DISCONNECT          AFTER DISCONNECT
──────────────────────     ──────────────────────────────────────
Both sides see messages    Each side sees only its own messages
Real-time collaboration    No new cross-company messages
Shared history             Each side retains its own history

Disconnecting does not delete messages. Each organization keeps their own copy of the conversation up to the point of disconnection.

Shared Channels for Common Scenarios

SCENARIO                           SETUP
──────────────────────────────     ──────────────────────────────────
Agency managing client project     1 shared channel per client
                                   #ext-[client-name]

Software vendor supporting         Shared channel for support tickets
enterprise customer                #ext-[company]-support

Two companies co-creating          Private shared channel for co-authors
a whitepaper                       #ext-collab-whitepaper

Brand working with PR firm         Shared channel for campaign updates
                                   #ext-prfirm-campaigns

Data Retention in Shared Channels

Both workspaces apply their own data retention policies to the shared channel. If your workspace deletes messages after 90 days and the partner's workspace keeps them forever, each side enforces its own policy independently. You cannot see messages that your own workspace has deleted, even if the partner still has them.

Key Takeaways

• A shared channel bridges two Slack workspaces so both teams see the same conversation.
• Both workspace admins must approve the Slack Connect invitation before the channel activates.
• Each organization names and controls access to the shared channel on their own side independently.
• Either side can disconnect the channel at any time — each side retains their own copy of the history.
• Data retention policies from both workspaces apply independently to messages in the shared channel.