The match started with the home crowd cheering on the Magpies, who began strongly. Joelinton had two early chances, first from a Kieran Trippier cross that was saved by Matz Sels, and then from a corner kick that Sels also managed to block.
Nottingham Forest struggled to deal with Newcastle's corner kicks, and the second half saw similar patterns. Morgan Gibbs-White's free kick was their only shot on goal, which Nick Pope easily punched away.
The hosts broke the deadlock just before the hour mark when Dan Burn fed Bruno Guimarães on the edge of the box, and he curled the ball beautifully into the top corner.
Newcastle continued to press, and another corner fell to Nick Woltemade, who rattled the underside of the crossbar from close range. Sels made several brilliant saves to keep the visitors in the game, but ultimately, Newcastle sealed the win from the penalty spot.
Woltemade scored his goal from the penalty spot, becoming only the third Newcastle player to score in their first three top-flight home matches.
This victory means Newcastle have kept a clean sheet in their last five home league wins, which will please their manager, Eddie Howe. Meanwhile, Nottingham Forest's new manager, Ange Postecoglou, is still searching for his first win after seven games in charge.