A Yaya Toure penalty sent the visitors on their way to an easy victory over Slaven Bilic's men, ensuring they progress to the fourth round of the competition.
Manchester City booked their ticket for the fourth round of the FA Cup, crushing West Ham 5-0 to serve the Hammers their heaviest defeat at London Stadium to date.
Defeat to Liverpool on New Year's Eve and a spiky reaction to a subsequent win over Burnley had turned the spotlight on Pep Guardiola before the trip to the capital, but that reverse at Anfield now stands as the lone blot in a run of five wins in six games.
West Ham had lost the last Cup game at their previous home Upton Park 2-1 to Manchester United and the Red Devils' local rivals made sure that the Hammers began life in the competition stickily at their new home.
Slaven Bilic's outfit were never in the contest and they trailed by three goals at half-time, with captain Mark Noble and talisman Dimitri Payet watching on from the bench.
Yaya Toure opened the scoring when he converted a penalty and City were cruising when Havard Nordveidt's own goal and a David Silva strike arrived within two minutes of each other.
Sergio Aguero reached a City landmark early in the second half and John Stones' first City goal capped a miserable night for the Hammers.
City stamped their authority on the game from the off with Pablo Zabaleta and Aguero forcing last-ditch work from Winston Reid and goalkeeper Adrian respectively.
The visitors continued to dominate in the opening stages and they were rewarded in the 33rd minute when Angelo Ogbonna was adjudged to have brought down Zabaleta inside the area and Toure made no mistake from 12 yards to open the scoring.
West Ham nearly found an instant equaliser when City keeper Willy Caballero failed to hold on to a Michail Antonio strike after a quick break, but Sofiane Feghouli inexplicably put the rebound wide with the open goal at his mercy, slight pressure from Gael Clichy seemingly putting him off.
The home side were made to pay for Feghouli's miss just minutes later when Nordtveit beat his own goalkeeper to double City's lead.
Bacary Sagna curled in a superb cross from the right after a lovely team move and Nordtveit was unlucky to guide the ball into his own net under heavy pressure from Raheem Sterling.
Things went from bad to worse for West Ham in the closing stages of the first half and Silva effectively put the match to bed in the 43th minute, keeping his cool after a low cross from Sterling as he took a touch before slotting home from close range.
Guardiola's side continued to push for more after the break and Aguero made it four when he cleverly lifted a shot from Toure over Adrian for his 154th goal for City in all competitions, surpassing Colin Bell in third place in the club's all-time scoring charts.
Bilic brought on Noble and Payet in an attempt to get back into the game, but the damage was already done as City remained in full control.
They even added a fifth in the 84th minute when Stones found the net with a header after Nolito's corner, Noble failing to clear on the goal-line as the hosts' ignominy was confirme
