Mark Stimson's Gills picked up their second pre-season victory but they were made to work hard for it by a committed Dartford side.
Gillingham took nine minutes to carve out the first chance of note, a neat one two with Rooney allowed Adam Miller to cut in behind the defence but John Guest was able to clear ahead of the lurking Mark McCammon
Moments later the Gills were in front after Andy Barcham forced his way into the area, his shot was blocked but Luke Rooney was on hand to slot home the loose ball.

The home sides first chance of the half came on 23 minutes when Jamie Day found space on the edge of the Gills box and fired a rasping volley narrowly over.
Dartford were enjoying a good spell of pressure and went close again in the 27th minute as full back Adam Gross cut a path through the visitors defence before drawing a save from Simon Royce with a low drive.
Soon after former Gillingham youngster Adam Burchell had Simon Royce scrambling to claw out his cheeky lob as the Darts grew in confidence.
Despite their pressure it was the visitors who scored again in the 37th minute, Andy Barcham pounced on a loose clearance from Adam Gross and slotted beyond the advancing Sam Mott from just inside the area.
Dartford's response was instant as the lively Burchell gathered a smart through ball from Seun Eferakorho and buried his finish into the far corner.
Then as half time approached the home side levelled the score with centre-half Adam Flanagan climbing above the Gills defence to power home Ryan Hayes corner.
HT 2-2
After a quiet opening to the half Gillingham took the lead again in the 51st minute, Chris Palmer fired a corner to the far post and Tom Wynter headed home unmarked.
Substitutions broke up the momentum of Dartford's play and it wasn't until the 67th minute that Gillingham mustered a shot on goal as Curtis Weston found space and sent a low drive fizzing wide of Mott's left hand upright.
Ten minutes later trailist Jordan Parkes crowned an impressive outing by netting the visitors fourth, slotting a low effort into the bottom left corner after a clever through ball from Stuart Lewis.
There was still life in the Darts who tested Alan Julian in the 85th minute. Jamie Day found room on the edge of the Gills area and struck a rising drive which Julian reacted quickly to block.
In the 89th minute Dennis Oli was unlucky not to claim a fifth, he collected Lewis defence splitting pass before firing an angled shot at goal but Mott got down well to thwart his ambitions.
Attendance: 1002
Gillingham 1st Half: Simon Royce, Barry Fuller, Aaron Brown, Garry Richards, John Nutter, Adam Miller, Kevin Maher, Rashid Yusseff, Luke Rooney, Mark McCammon, Andy Barcham
Gillingham 2nd Half: Alan Julian, Sam Long, Aaron Brown, Tom Wynter, Jordan Parkes, Stuart Lewis, Jack Payne, Curtis Weston, Dennis Oli, Luis Cumbers, Chris Palmer.
Subs not used: Andy Pugh, Aaron Beckles
Dartford: Andrew Young (28 Sam Mott), Seun Eferakorho (62 Danny Crounch), Adam Gross (75 Chris Wimshurst), Adam Flanagan (46 John Beales), John Guest (46 Jamie Coyle), James White (68 Kieran Dingri), Ryan Hayes (75 Husein Isa), Jamie Day, Adam Burchell, Karl Dent (46 Billy Burgess), Elliott Bradbrook (46 Danny Dafter).
