City raced into a commanding four-goal lead in the first half at the Etihad, starting with a Foden strike on eight minutes before Haaland netted a quick-fire double, with Foden adding a further goal on the stroke of half-time.
United clawed a goal back through a stunning left-footed strike from Antony -- his second goal in as many Premier League games for the club -- but Haaland completed his hat trick shortly after, with Foden adding a third of his own on 73 minutes.
Haaland becomes the first player in Premier League history to score a hat trick in three consecutive home games.
United striker Anthony Martial struck a pair of late consolation goals in the final 10 minutes of the match -- first heading in a rebound, the second from the penalty spot -- but could not cut the deficit enough to trouble City in a resounding Manchester derby victory.
Sunday's result means City move back to within one point of leaders Arsenal.
"We scored six goals, what can I say, it's amazing," Haaland told Sky Sports. "To win at home, score six goals, it's nice.
"You can feel it all the time. You can see the passes we give each other. We always want to go forward and to attack. It's what I love about the team."
Despite the comfortable nature of the victory, City boss Pep Guardiola was not quick to heap on his team.
"Perfection doesn't exist, it's impossible," Guardiola said. "But we must try to look there. We did good, we can do better, many, many players had sloppy passes. This is not good. We have to be more consistent. In some areas we were still not good.
"Some players were not good today so they have to improve."