Leo Dos Reis, high on confidence after scoring in a narrow 3-2 defeat to West Bromwich Albion two weeks earlier, poached his second of the campaign to hand Blues a deserved win.
There was little between the two sides in a competitive opening 20 minutes, with Dos Reis’ volley from Jordan Graham’s free-kick the only notable chance in a tight first-half.
Sunderland looked lively down their left, Benji Kimpioka enjoyed a superb battle with the impressive Marcel Oakley, who kept the Swedish youth international at bay.
There were no changes at the break as Blues burst out of the blocks, Graham flashing a wicked ball across the box early on whilst Mitch Roberts also fired over.
The game was beginning to open up and the hosts would get their reward ten minutes after the restart.
Another Graham delivery from the right was whipped in towards the back post and Dos Reis fired past Jacob Carney for his second goal in as many games.
Blues were on top and nearly added a second when Remi Walker’s shot from the edge-of-the-box bounced agonisingly off the crossbar just three minutes after the opener.
Kyle Hurst would fire wide late on as Steve Spooner's team, threatened a second but in the end, they would hold out for a deserved first win in the Premier League 2.
Blues: Neil Etheridge, Marcel Oakley, Juan Castillo, Alfie Chang, Tommy Fogarty, Mitch Roberts ©, Jordan Graham, Remi Walker, Leo Dos Reis (Zohore, 80), Caolan Boyd-Munce, Kyle Hurst (Williams, 80).
Substitutes not used: Rico Browne, Archie Matthews, Jordan James.
Booking: Hurst 78.
Sunderland: Jacob Carney, Kenton Richardson, Nathan Newall (Dyce, 67), Tom Scott, Oliver Yonnger, Patrick Almond, Ellis Taylor (Kelly, 80), Harrison Sonha, (Kachosa, 67), Will Harris, Stephen Wearne ©, Benji Kimpioka.
Substitutes not used: Jack McIntyre, Luke Chapman.
Booking: Oliver Yonnger 29,
Report: Newcastle United Under-23s 4-0 Blues Under-23s