Bradford dented the Sky Bet League One play-off hopes of Portsmouth with only their second win in 16 matches.
Pompey had the chance to move into the top six but were denied by Nat Knight-Percival, substitute Matthew Lund and leading scorer Charlie Wyke - who gave the Bantams a 3-1 victory.
Knight-Percival put Bradford in front in the 14th minute. Tony McMahon's corner was headed into the defender's path by Matt Kilgallon and Knight-Percival hooked the ball high into the net.
Colin Doyle then made two saves from Wolves loanee Connor Ronan and Portsmouth captain Brett Pitman to preserve Bradford's lead before half-time.
Portsmouth equalised in the 61st minute with a superb goal from Pitman - his 22nd of the League One season.
The Pompey skipper took a pass from substitute Stuart O'Keefe and scored with a 25-yard shot, the ball taking a slight deflection as it flew past the diving Doyle and into the corner.
Lund, on loan from Burton, restored Bradford's lead in the 71st minute with his first goal for the club, racing on to Wyke's flicked pass before forcing his way past Matt Clarke.
Wyke then put the result beyond doubt in the fifth minute of added time, slotting the ball into the empty net after keeper Luke McGee parried McMahon's 20-yard free-kick.