Aleksandar Mitrovic scored his 34th Championship goal of the season as Fulham moved a step closer to promotion.
Mitrovic headed Harry Wilson’s cross into the far corner of the net to clinch another victory for the Whites, who are 11 points clear at the top of the table.
Cardiff did cause them some problems, with keeper Marek Rodak doing well to prevent James Collins equalising.
Fulham were not at their best but were nevertheless deserved winners as they were the better side throughout.
They arguably should have been awarded a penalty when Aden Flint appeared to handle the ball in the box seven minutes into the second half.
And Bobby De Cordova-Reid, playing against his former club, had a header tipped over by Cardiff’s ex-QPR keeper Alex Smithies.