Boro will head to Rotherham United in July as part of the pre-season programme.
Michael Carrick's squad will face the Millers on Wednesday 19 July (7pm).
Confirmation of the trip to South Yorkshire follows the announcement that Boro will play games against Hartlepool United on Friday 14 July (7pm), followed by a trip to face York City on Saturday 15 July (1pm).
Boro were beaten 1-0 at Rotherham last season, but were 1-0 winners on our previous visit, a pre-season friendly in 2021, when Paddy McNair scored the decisive goal.
Further pre-season friendlies will be confirmed in due course.