It was another dull, disjointed performance from a Newcastle side who had only conceded four goals at home this season, only to allow a striker once deemed surplus to requirements to score three times in one game.
Newcastle took the lead in the 23rd minute when Alexander Isak won a penalty as he tried to spin away from Forest full back Ola Aina, and the Sweden striker stepped up to stroke home the spot-kick low to left of keeper Matt Turner.
Wood, who was loaned to Forest by Newcastle in January before being signed permanently, brought his side level just before the break with a close-range tap-in from Anthony Elanga’s centre.
Forest’s Morgan Gibbs-White flashed a header just wide and Elanga should have put the visitors ahead six minutes after the break, but his weak effort with the goal at his mercy was easily dealt with by Newcastle keeper Martin Dúbravka.
Newcastle’s defence failed to heed those warnings, however, and Wood put them ahead in the 53rd minute with a brilliant solo effort from another counter-attack, dinking the ball past Dubravka with his left foot after a clever run.
Newcastle enjoyed plenty of possession but once again their attack struggled to gel. Only Isak looked dangerous when he got hold of the ball around the Forest box, and the visitors were always ready to pounce once the attacks broke down.
New Zealand international Wood completed his hat trick on the hour mark with another well-taken goal on the counter, rounding Dubravka and coolly slotting home to secure a well-deserved win.
Wood’s goal celebrations were muted, but he couldn’t hide his delight as he took the applause of the Forest fans at the final whistle.
“It is nice coming back to Newcastle, I really enjoyed my time here, it is a great bunch of lads and staff,” he told the BBC.
“We needed three points and it was fantastic for the side to get it. This is a tough place to come, the boys did extremely well.”