Newcastle included Cisse in their matchday squad for the fist time since his falling out with the club regarding their sponsorship deal with Wonga. Meanwhile, summer signings David Cornell and Gary Harkins earned a place in the starting lineups for the hosts.
Cisse's return to the side proved to be a successful one, as the Senegalese collected Sammy Ameobi's cross and lifted a delightful finish over Cornell in the 19th minute.
Ameobi troubled the home team's defence once again just a couple of minutes later, before Cornell reacted superbly to keep out Dan Gosling's effort.
Debuchy doubled the Magpies' lead on 26 minutes, as the marauding full-back finished calmly after collecting Vurnon Anita's through-ball.
Gosling almost extended Newcastle's lead further as the game approached half time, but his powerful drive fizzed just over the crossbar.
Gary Teale was at the heart of everything St Mirren did, but the former Wigan Athletic winger was marshalled well by the Newcastle defence throughout the second half.
Both sides made a number of changes as the game wore on, and Newcastle held on to secure a comfortable 2-0 north of the border.