The 2011 winner bounced back from a disappointing Premier League defeat at Southampton with an authoritative display against a lackluster performance from Neil Warnock's men.
Yaya Toure opened the scoring early on after a powerful run, before Sergio Aguero bagged from the spot to double the lead inside 15 minutes.
Carlos Tevez’s early second-half goal and Aguero’s cool finish compounded Leeds’ miserable afternoon, and the 2011 winner will go into the last eight as one of the favorites.
Roberto Mancini rang in the changes, with only five of the starting lineup from the 3-1 defeat at Southampton keeping their place. Costel Pantilimon came in for Joe Hart while Gareth Barry was left out of the squad entirely, and James Milner earned a start against his former club.
Leeds also lined up with a different goalkeeper as Neil Warnock drafted in Jamie Ashdown for Paddy Kenny in one of four changes from the 1-0 defeat against Middlesbrough in midweek.
It didn’t take long for the home side to make its mark on the game, as Tevez collected the ball on the edge of the box before flicking a perfect pass into the path of Toure, who made no mistake in rounding Ashdown and slotting the ball into the net.
David Silva and Tevez both blasted shots wide before City moved two up within the opening quarter of an hour after Tom Lees was penalized for a tug on Aguero in the box, and the diminutive striker stepped up to drive the ball into the top left corner.
El Hadji Diouf headed over the bar for a shell-shocked Leeds, but City was still dominant in possession, and Toure was denied his second of the afternoon after Ashdown tipped over the midfielder’s powerful 25-yard volley, before Garcia flashed a header wide from a corner.
The home side cruised through the last minutes of the half but Ross McCormack had an excellent chance on the stroke of halftime from a free kick at the other end, only forcing a simple parry from Pantilimon.
City quickly moved further in front after the break as good work from Silva set Aguero free on the left, and the striker lifted it across goal past Ashdown for Tevez to bundle home on the line.
Any pushes forward from Leeds were easily dealt with by City’s defense, who had hardly been tested by the Leeds all afternoon. At the other end, Milner nearly made it four with a low drive from distance which rifled into the side netting.
The superb Aguero broke forward yet again, after linking up with Silva, and tried to find Tevez with a low cross which, unfortunately for City, was just behind the Argentina international’s run.
Jack Rodwell came off the bench and should have scored within moments of coming on after Toure forced a parry from Ashdown, and the rebound looped into the path of the midfielder who headed on to the bar with the goal at his mercy.
Leeds fashioned a good chance shortly afterwards as Aidan White whipped in a superb cross from the right side, which Luke Varney met six yards out but couldn’t direct anywhere near the target.
Then, with just over 15 minutes remaining, Aguero doubled his tally for the afternoon, latching on to Silva‘s ball over the top and diverting it past Ashdown to go in off the post.
Substitute Edin Dzeko forced a fine save from Ashdown and Hugo Zabaleta fired wide late on, but the result was well beyond doubt and City will feel it has an excellent chance of winning a second FA Cup title in three seasons.