The first chance fell to the Dons when Maguire fired in a shot from distance that went narrowly over while, at the other end, Calum Smith found himself clear but his effort, with Mark Thomas in close attention, went narrowly wide.
Willie John Kiely was next to show, with an 18th minute effort that was well held by Greig Paterson. A great run and cross by David Muir ended with Ian Williamson hooking the ball wide from six yards as the Pars threatened.
The Dons shoule have gone in front in 31 minutes when Kiely fired wide after good work from Chris Maguire but four minutes later it was the visitors who drew first blood when Fraser Stewart was beaten to a long ball by MUIR, who headed home from close range.
In the 58th minute, Aberdeen took the lead with a fabulous MAGUIRE solo effort, with the striker leaving three defenders trailing in his wake before slotting the ball past Paterson.
In the closing stages Dunfermline pushed forward and Stewart kept the Dons ahead with a fantastic save from Williamson with nine minutes remaining and four minutes later, Neil Cooper's team made sure of the victory when Michael Paton and Neil McVitie provided the build-up before the ball came to Andy BAGSHAW at the edge of the box and the number seven coolly curled the ball home, giving Paterson no chance.