West Ham had their fair share of early possession, but it was the hosts who carved out early opportunities, with Callum Hudson-Odoi and Nicolas Domínguez both shooting wide.
The visitors continued to push for an opening, but found out why Nuno Espírito Santo’s side entered this contest having conceded just seven league goals, as a Max Kilman burst forward was halted on the edge of Forest’s box.
West Ham couldn’t offer the same resistance, as Alex Moreno glided outside Konstantinos Mavropanos and crossed for Chris Wood to head in his fourth goal across three league games.
Roared on by the City Ground crowd, Forest kept pressuring the visitors, with Hudson-Odoi shooting straight at Lukasz Fabiański after an Ola Aina’s long throw was unconvincingly cleared.
There was a fleeting moment of Hammers hope before the break, as Paqueta hit their first shot of the half, which seemed destined to go in until Wood cleared it off the line.
The disbelief from that moment was then compounded further, as Edson Alvarez foolishly slid in to foul Anthony Elanga just eight minutes after receiving a first booking for pulling Murillo’s shirt.
Julen Lopetegui responded with a double change ahead of the restart, and his side showed intent, although Jarrod Bowen struck over the crossbar with the Hammers’ first real opening after half-time.
Forest maintained a threat of their own though, with Hudson-Odoi curling an effort past Fabianski’s far post, before another beat the Hammers goalkeeper and nestled in the net.
Moments after coming off the bench, Elliot Anderson won a free-kick from Jean-Clair Todibo and laid the ball back to the winger, whose attempt took the slightest of touches off Mavropanos on its way in.
After Moreno and Nikola Milenkovic sent attempts wide, Ola Aina capitalised on a lax flick from Todibo by smashing a left-footed strike into the top corner as Forest comfortably secured their third consecutive victory – and the second clean sheet therein – to enter the Premier League top four for now.
In contrast, West Ham are without a shutout in their last eight league games and have lost four of those.
Flashscore Man of the Match: Callum Hudson-Odoi (Nottingham Forest)