Bruno Zuculini opened the scoring for the Premier League champions in the third minute, only for CJ Sapong to draw the MLS title-holders level in the 30th minute at Sporting Park.
Dedryck Boyata restored City's one-goal buffer when he lost Sporting's Aurelien Collin to nod home from a free-kick in the shadows of half time.
Aleksandar Kolarov converted a 72nd-minute penalty to seal the win for Manuel Pellegrini's outfit, before trialist Kelechi Iheanacho added a fourth late on.
City are in Group B for the pre-season tournament in North America, which first sees them take on Milan on Sunday.
The tone of the contest was set early as Zuculini finished with power and precision into the bottom left corner of Sporting KC's goal.
Peter Vermes' men almost replied immediately, with Sapong's volley from a Soony Saad cross coming back off the crossbar while Dom Dwyer had a goal ruled out due to an offside flag from a free-kick in the 10th minute.
City's attacking game rarely let up, with Nigerian teenager Iheanacho forcing Sporting goalkeeper Andy Gruenebaum to tip long-range shots away twice in two minutes.
Sporting found a deserved equaliser though, as Benny Feilhaber's cross into the area found Sapong, who had time to take a touch and finish past the stranded Willy Caballero on the half-hour mark.
Stevan Jovetic had a one-on-one chance with Gruenebaum late in the half, only for a last-gasp challenge from Collin to deny the Montenegrin forward.
Collin almost got the job done at the other end moments later, as he was at the back post for a flicked-on header - but he could not get the crucial touch.
However, that man lost Boyata at the set-piece as City took a lead into the interval.
Both coaches swung changes at half-time, Sporting KC bringing in a fresh XI while City subbed Micah Richards for Gael Clichy.
Sal Zizzo was at the heart of multiple Sporting KC chances for an equaliser, sending a diving header wide and also finding Michael Kafari in a dangerous area - only for his team-mate unable to finish under pressure.
But City went on to seal the victory after Scott Sinclair was fouled in the area by Kafari, and Kolarov converted the spot-kick before Iheanacho capped an impressive cameo with a goal.
