Former Bradford players Devante Cole and Jordy Hiwula scored two of the goals as Fleetwood gained revenge for last season's Sky Bet League One semi-final play-off defeat with a 3-0 victory at Valley Parade.
Fleetwood's win -their first at Valley Parade - ended Bradford's six-match unbeaten league run that had lifted them into third place. All the goals came in a 19-minute spell in the second half.
After a dour first period, Fleetwood shook the Bantams by going in front in the 51st minute following a mistake by Bradford skipper Romain Vincelot.
The goal was scored by Hiwula, who was Bradford's leading scorer last season during a season-long loan from Huddersfield.
Cole, who joined Fleetwood from Bradford two seasons ago, intercepted Vincelot's pass before delivering a through ball for Hiwula to score.
The visitors scored a second five minutes later after goalkeeper Colin Doyle was booked for bringing down Cole on the edge of the penalty area. Kyle Dempsey's free-kick rebounded off the defensive wall, but he retrieved the ball to cross for Cole to score with a close-range shot.
Ashley Hunter then put the result beyond doubt with a third goal, two minutes after coming on as a substitute. He took a pass from Cole in a Fleetwood counter-attack before scoring with a shot into the far top corner.