Trippier played the first half, with the game ending 1-1. Anthony Munda put Newcastle ahead before Timur Tutierov levelled late on for Sunderland.
Just over a month on from his participation at Euro 2024 and defeat in the final versus Spain, the England defender turned out in front of around 1,000 spectators at Whitley Park.
Trippier was an unused substitute during Newcastle’s 1-0 opening-day win over Southampton on Saturday, and we understand he put himself forward for a role with the second string.
Mail Sport revealed on Monday tea-time that the 33-year-old was set to play the first 45 minutes, and he enjoyed a solid half at right back before making way at the break, along with fellow first-teamer Matt Targett.
Kieran Trippier made a shock appearance for Newcastle Under-21s against Sunderland
Trippier’s future on Tyneside is uncertain - he has 12 months on his contract - and we reported on Monday that Bruno Guimaraes has now been promoted to team captain on a permanent basis.
Eddie Howe was in the stands at Whitley Park and we understand the head coach wants his vice-captain to remain at the club.