The FA Premier League Northern Division side stormed into a 3-0 lead in only 15 minutes.
Campbell got the opener, with the Bantams quickly doubling their lead through Rachel Lee, who met a superb through ball from Charlotte Stuart.
Campbell then made it 3-0 before going on to complete her hat-trick, with Sarah Danby taking the tally to five before the break.
Leeds continued to press despite the scoreline but were unable to create a real goal scoring chance in the first half.
The second period turned out ot be much more even and the only goal was from a City corner by Chantelle O’Hara that forced an un unfortunate own-goal.