Published: 16:30, 02 January 2016
Bradley Dack bagged his 13th goal of the season as the Gills made it four wins on the spin.
Rory Donnelly added to Dack’s fourth-minute strike and a late Doug Loft goal completed the victory.
Bradford ended the game with 10 men after Nathan Clark was sent off for pulling back substitute Elliott List, who was clean through.
Victory moved the Gills up to second in League 1.
Justin Edinburgh stuck with a familiar line-up for the visit of the Bantams.
His team, unchanged from the one that started against Colchester on the Monday, had won their previous three prior to the visit of the Yorkshire side.
The Gills, shooting towards the Rainham End from the off, made a blistering start to the game, having survived some early pressure from the visitors.
A goal after four minutes against the run of play from Dack, hitting home from 25 yards, put Gillingham ahead.
The midfielder turned provider on 11 minutes as the Gills doubled their lead, putting Donnelly in on goal, and he broke his recent barren run with a curling effort to make it 2-0.
Donnelly, scoring his first in 12 games, nearly had another two minutes later, latching onto Jake Hessenthaler’s pass, but this time Stephen Darby cleared off the line.
It was almost game over for Bradford but they responded well and should have had a goal of their own in the first half.
Reece Burke had a chance cleared off the line by John Egan and Rory McArdle’s follow-up was stopped by Stuart Nelson with his legs, as the Bradford man turned away to celebrate.
Devante Cole missed a great chance from in front of goal, putting Kyel Reid’s cross over, and the Bradford striker also headed a chance wide.
Gillingham ended the half with wide efforts from Aaron Morris and Max Ehmer.
The start of the second half failed to produce the fireworks of the first 45 as the Gills looked to keep Bradford quiet.
Cole put a chance over for Bradford with 65 minutes gone and Kyel Reid shot wide. Billy Clarke and Tony McMahon also fired the wrong side of a post as the Gills kept the visitors at arm’s length.
Gillingham made it three with a minute left. Dack picked out Ryan Jackson and from his cross Loft slotted home from close-range.
In stoppage-time substitute striker Luke Norris left the field injured following a challenge in the box. List could have added a fourth for the Gills, but was denied by Clarke's foul.
Gillingham: Nelson, Jackson, Garmston, Egan, Ehmer, Wright (Loft 76mins), Hessenthaler, A Morris, Dack, Donnelly (Norris 65mins (List 90mins)), Samuel. Subs not used: G Morris, Oshilaja, Osadebe, McGlashan.
Bradford: Williams, Darby (Marshall 79mins), Meredith, McArdle, Burke (N Clarke 53mins), Knott (B Clarke 62mins), Liddle, McMahon, Reid, Hanson, Cole. Subs not used: Cracknell, Leigh, Routis, James.
Attendance: 6,446 (361 away)