The match had a very feisty opening with three players booked inside the opening 25 minutes.
Leeds were on top of the proceedings, however, with Luke Varney working an early chance but firing wide.
They were dominating with corners and crosses into the box but David Marshall was standing firm between the posts in the league leaders' net.
Leeds started to dominate the game and Ross Barkley was the next to test Marshall but they were still unable to beat him.
Despite Leeds's first-half performance it was Cardiff who took the lead in the 64th minute, Campbell bundling in from close range.
Leeds were unable to mount a comeback and Cardiff took the three points to extend their lead at the top.