Slack Trello 2-way Unito Integration

How to Quickly Send Slack Messages From Trello Cards

There are a number of practical reasons to connect Slack with Trello using an automated workflow solution. Both Slack and Trello have their own unique benefits for working professionals operating remotely, and in-person with teammates. Above all, they’re ideal for collaboration and communication throughout a project’s lifecycle. Supporting Slack and Trello with automation is a logical next step for any power user, since integrating these powerful tools enables you to:

  • Create a new card in Trello whenever you send a message in a specified Slack channel.
  • Send a message in Slack whenever you create a Trello card that includes a specific label, list, or member of your team.

It’s remarkably easy to build an automated workflow to establish this kind of functionality. All it takes is a simple set of rules and field mappings for Unito to automate a 2-way integration that connects Slack with Trello.

Why connect Slack with Trello with Unito?

The kind of functionality you get with a 2-way sync that connects Slack with Trello is great for keeping colleagues in the loop. Many professionals in 2022 across industries or teams rely on Slack and Trello including marketing, sales, IT support, finance and accounting, operations, human resources, procurement, and so on.

You can use this type of workflow to send automatic notifications to teams in Slack about new business or key information. As an alternative, you could send a message to your Trello-connected Slack channel about an important task you don’t want to forget by turning it into a card.

This guide will show you how to connect Slack with Trello to sync conversations and cards quickly and effectively. Similar steps will apply to syncing Slack with other project management tools including: Asana, Wrike, Jira,, ClickUp, Basecamp and many others.

Before we connect Slack with Trello

  • Ensure you have an account with the right permissions in both Trello and Slack. You don’t need to be the account owner, but you do need access to the Trello board and Slack channel you’ll be connecting to Unito.
  • (optional) If you’re in Trello currently, you can add Unito as a Power-Up to an existing Trello board.


Feel free to skip ahead if you’re already in the middle of building this workflow:

Step 1. Connect Slack and Trello to Unito

Step 2. Set a flow direction between Slack and Trello

Step 3. Set rules to sync Slack and Trello

Step 4. Select field mappings to sync Slack messages and Trello cards

Step 5. Save, close and launch your flow

Step 1. Connect Slack and Trello to Unito

Navigate to the Unito App and select +Create Flow. On the next screen, select Start Here to connect Slack and Trello. Choose the accounts you wish to connect to Unito. Then, specify a specific Trello board and Slack channel. Later, you’ll be able to specify the methods by which new messages and cards will sync to the other tool.

Connect Slack and Trello with Unito tool selection
In the above example, Fanny has connected her Trello board “Project Board” to the Slack channel “test-channel-releases” for the purposes of our demo.

When you’re ready, select Confirm.

Step 2. Set a flow direction between Slack and Trello

Flow direction allows us to tell Unito whether we want new Trello cards to create messages in Slack, vice versa, or both. For the purposes of our demo, we’ll show you how to build a 2-way flow, but feel free to experiment with your own preferences.

Set a flow direction between Slack and Trello with Unito

As you’ll see in Step 4, we will also be able to choose a flow direction for specific fields (messages, replies, etc.) in case we only want to send certain information in a single direction (e.g., sync Slack replies to Trello cards, but not Trello comments back to Slack messages).

Learn more about flow directions.

Select Confirm when you’ve chosen a flow direction. 

Step 3. Set rules to sync Slack and Trello

Select Add a new trigger to choose rules that tell Unito what actions in Trello or Slack will enable new cards or messages to appear in the other.

Set rules to sync Slack and Trello with Unito
In this example, we’ve told Unito to send a message in Slack every time a Trello Card is added to our “Done” list.

Rules give you a lot of freedom and flexibility to decide how Unito can best help you eliminate manual tasks, such as updating teams about project status, assigning work to specific people, requesting support or information, etc.

Note: Since our Slack integration is still fairly new, there are a limited number of ways you can apply rules from Slack to your other tools. We recommend creating a channel specifically for your integration with Trello to keep things simple.

Find out more about setting rules.

Step 4. Select field mappings to sync Slack messages and Trello cards

Select + Add mapping, then Select a field in both Trello and Slack to pair two fields together. Unito considers any detail of your Slack message or Trello card to be a field. In Trello, that can mean comments, titles, descriptions, checklists, etc. In Slack, we recommend sticking to messages, replies, and link to message.

Each field can be synced one-way in either direction or bidirectionally.

Select field mappings to sync Slack messages and Trello cards with Unito
In our demo, we’re keeping it simple by only syncing replies to comments and messages to Trello card titles.
Synced Slack and Trello interfaces in an automated 2-way Unito workflow
Here’s an example of a synced Slack + Trello integration with Unito. A message from Slack created a card in Trello, and vice versa.

Learn more about Field Mappings

Click Confirm when you’re satisfied with your field mappings to proceed.

Step 5. Save, close and launch your flow!

And that’s it! You’ve just completed a flow to connect Trello with Slack. Congratulations!

If you’ve followed the steps above, your flow will now: 

  • Create Trello cards based on Slack messages from your specified channel.
  • Send Slack messages based on the triggers set in your rules.
  • Enable teams to collaborate quickly and efficiently between Slack and Trello with an automated 2-way sync.
Slack and Trello synced with Unito
Left: One of our synced Slack threads
Right: A synced Trello card

If you have any questions, don’t hesitate to reach out and let us know. 

What’s next after connecting Slack with Trello?

If you’re interested in seeing what else you can do with Unito, here are some articles to help you power up your workflows:

  • You can duplicate this flow to sync other types of Slack messages to any tool in your stack (including other Trello boards).