How to Create Trello Cards from Slack Messages with Power Automate

Create > Automated cloud flow > Slack

Create new automated flow

Navigate to make.powerautomate.com and sign in with your Microsoft account. Click 'Create' in the left sidebar, then select 'Automated cloud flow'. Name your flow 'Slack to Trello Cards' and search for 'Slack' in the trigger selection. Choose 'When a message is posted to a channel' as your starting trigger.

1. 1Click 'Create' in the left navigation
2. 2Select 'Automated cloud flow'
3. 3Type 'Slack to Trello Cards' as flow name
4. 4Search for 'Slack' in the trigger box
5. 5Choose 'When a message is posted to a channel'

Slack trigger > Sign in

Connect your Slack workspace

Click 'Sign in' next to the Slack connection field. This opens a new browser tab asking for Slack permissions. Select your workspace from the dropdown and click 'Allow' to grant Power Automate access to read messages and channel information. The connection process takes about 30 seconds to complete.

1. 1Click 'Sign in' in the Slack trigger configuration
2. 2Select your Slack workspace from the dropdown
3. 3Click 'Allow' to grant permissions
4. 4Wait for the green connection confirmation

Slack trigger > Team > Channel

Configure channel monitoring

Select your Slack team from the Team dropdown, then choose the specific channel you want to monitor from the Channel dropdown. The channel list shows all public channels you have access to. Private channels only appear if you're already a member. For keyword-based triggers, you'll add filtering logic in the next step.

1. 1Select your workspace from the Team dropdown
2. 2Choose the target channel from Channel dropdown
3. 3Note the channel ID that appears in parentheses
4. 4Click outside the dropdown to confirm selection

New step > Control > Condition

Add keyword filtering condition

Click '+ New step' below the Slack trigger and search for 'Control'. Select the 'Condition' action to add message filtering logic. This prevents every message from creating Trello cards. Set up the condition to check if the message text contains specific keywords like 'task', 'todo', or 'action item' that indicate a card should be created.

1. 1Click '+ New step' under the Slack trigger
2. 2Search for 'Control' in the connector list
3. 3Select 'Condition' from the actions
4. 4Click in the left value box to open dynamic content

Condition > Choose a value > Dynamic content > Text

Configure keyword detection logic

In the condition's left value field, select 'Text' from the dynamic content panel under the Slack section. Change the operator from 'is equal to' to 'contains'. In the right value field, type your trigger keyword like 'create card' or 'action item'. You can add multiple conditions using 'Add' to check for different keywords or reaction emojis.

1. 1Click the left 'Choose a value' field
2. 2Select 'Text' from Slack dynamic content
3. 3Change operator dropdown to 'contains'
4. 4Type 'create card' in the right value field
5. 5Click 'Add' to include additional keyword checks

Condition Yes > Add an action > Trello > Create a card

Connect to Trello

In the 'Yes' branch of your condition, click 'Add an action' and search for 'Trello'. Select 'Create a card' from the Trello actions list. Click 'Sign in' to connect your Trello account. Power Automate redirects to Trello where you'll authorize access to your boards and cards. The authentication process includes selecting which Trello workspace to connect.

1. 1Click 'Add an action' in the Yes branch
2. 2Search for and select 'Trello'
3. 3Choose 'Create a card' action
4. 4Click 'Sign in' for Trello connection
5. 5Authorize Power Automate in the Trello popup

Create a card > Board > List

Select target board and list

Choose your destination Trello board from the Board dropdown. All boards you have access to appear in this list, including shared boards. After selecting a board, the List dropdown populates with that board's lists. Choose the list where new cards should appear, typically 'To Do', 'Backlog', or 'Incoming Requests' depending on your board structure.

1. 1Select target board from Board dropdown
2. 2Wait for List dropdown to populate
3. 3Choose the destination list (e.g., 'To Do')
4. 4Verify the correct board and list are selected

Create a card > Name > Dynamic content

Map message content to card fields

Configure the card creation fields using Slack message data. Click in the Name field and select dynamic content to build a card title. Use a combination of the channel name and timestamp, or extract the first few words from the message text. For the Description field, include the full message text, author name, and a link back to the original Slack message for context.

1. 1Click in the Name field
2. 2Select 'Channel' and 'Timestamp' from dynamic content
3. 3Format as 'Action from #[Channel] - [Timestamp]'
4. 4Click in Description field
5. 5Add 'Text', 'User', and 'Permalink' from Slack data

Insert new step > Trello > Get cards in a list

Add duplicate prevention logic

Above the Trello action, add another step to check for existing cards. Click 'Insert a new step' between the condition and Trello action. Search for 'Trello' and select 'Get cards in a list'. Configure it to search your target list, then add another condition to check if a card with the same Slack message timestamp already exists. This prevents duplicate cards from the same message.

1. 1Click 'Insert a new step' before the Trello action
2. 2Search for 'Trello' and select 'Get cards in a list'
3. 3Select the same board and list as your create action
4. 4Add another condition to check for existing timestamps
5. 5Move the create card action inside the new condition's 'No' branch

Save > Test > Manually

Test and activate the flow

Click 'Save' in the top right to save your flow configuration. Then click 'Test' and choose 'Manually' to test with a real Slack message. Go to your configured Slack channel and post a message containing your trigger keyword. Return to Power Automate within 2-3 minutes to see the test results and verify the Trello card was created correctly.

1. 1Click 'Save' in the top toolbar
2. 2Click 'Test' next to the Save button
3. 3Select 'Manually' test option
4. 4Post a test message in your Slack channel
5. 5Check the flow run history for results

Add this expression in a Compose step before the Trello action to clean message formatting and extract the first 50 characters for the card title. Paste this in the Compose action's Inputs field.

{
  "cleanTitle": "@{take(replace(replace(triggerOutputs()?['body/text'], '<[^>]*>', ''), '&nbsp;', ' '), 50)}",
  "fullDescription": "@{triggerOutputs()?['body/text']}\n\nPosted by: @{triggerOutputs()?['body/user']}\nChannel: #@{triggerOutputs()?['body/channel']}\nOriginal: @{triggerOutputs()?['body/permalink']}",

{
  "cleanTitle": "@{take(replace(replace(triggerOutputs()?['body/text'], '<[^>]*>', ''), '&nbsp;', ' '), 50)}",
  "fullDescription": "@{triggerOutputs()?['body/text']}\n\nPosted by: @{triggerOutputs()?['body/user']}\nChannel: #@{triggerOutputs()?['body/channel']}\nOriginal: @{triggerOutputs()?['body/permalink']}",
  "priorityLevel": "@{if(contains(triggerOutputs()?['body/text'], 'urgent'), 'high', 'normal')}"
}