Raheem Sterling and Ilkay Gundogan were also on target as dominant City humiliated Chelsea out of top four.
Sterling broke the deadlock for City 4 minutes into the game as Bernardo Silva cross deflected to Sterling, who arrived at the back post and fired past Kepa.
13 minutes into the game, Aguero doubled the tally for City with a stunning right-footed strike from 25 yards into the top-right corner.
6 minutes later, it was 3-0 for City. Chelsea with a poor defending as Barkley headed City cross back into his area, taking his defenders out of the game and Aguero was there waiting for the ball to drop and he strikes it past Kepa.
54 minutes on, Fernandinho picks out Sterling on the left and goes past Azpilicueta. The Spaniard dives in and takes down Sterling. The referee immediately points to the spot.
Aguero stepped up for the spot kick and sends Kepa the wrong way, passing the ball into the bottom-right corner to bag his 11th Premier League hat-trick, equalling the record set by Alan Shearer.
80th minute, Sterling doubled his tally with a simple tap into the net from six yards out after a lovely passing move from the hosts with Zinchenko getting his second assist of the game for a well-directed, left-footed cross.
An extremely poor performance from the Blues as they failed to register a single goal, with Pep side smiling away with huge goal margin and 3 points.