Add HTML into a paginated report (Report Builder)
Applies to: 
Microsoft Report Builder (SSRS)
Power BI Report Builder
Report Designer in SQL Server Data Tools
Using a placeholder, you can import HTML from a field in your dataset for use in the paginated report. By default, a placeholder represents plain text, so you need to change the placeholder mark-up type to HTML. For more information, see Importing HTML into a report (Report Builder).
Note
You can create and modify paginated report definition (.rdl) files in Microsoft Report Builder, Power BI Report Builder, and in Report Designer in SQL Server Data Tools.
Add HTML from a field in your dataset into a text box
On the Insert tab, select List. Choose the design surface, and then drag to create a box that is the size you want.
The Dataset Properties dialog opens. You can use a shared dataset or a dataset embedded in your report. For more information, select Dataset Properties dialog, query (Report Builder) or Dataset Properties dialog, query.
On the Insert tab, select Text Box. Drag the box from the list to create a box that is the size you want.
Drag an HTML field from your dataset into the text box. A placeholder is created for your field.
Right-click the placeholder, and then select Placeholder Properties.
On the General tab, verify that the Value box contains an expression that evaluates to the field you dropped in step 3.
Select HTML - Interpret HTML tags as styles. This causes the field to be evaluated as HTML.
Select OK.