Title rivals Hibernian's third defeat in a row at Queen of the South left the door open for the Glasgow side to extend their lead at the top of the Ladbrokes Championship to 14 points, with just nine games remaining .
And they took it as the impressive Forrester - the scorer of Gers' last-gasp weekend winner against St Mirren - put on his brightest display in a blue jersey since sealing his January move from Doncaster.
Given the task of setting the tempo for Mark Warburton's team, the Englishman pulled the strings in midfield before giving the hosts a first half lead, while skipper Lee Wallace sealed the victory with a second just after the interval.
Rangers now just need five more wins to seal their Premiership return.
With Saturday's Scottish Cup clash with top-flight Dundee on the horizon, Warburton rested veteran striker Kenny Miller and midfielders Nicky Law and Barrie McKay.
That gave Forrester his chance to start alongside Billy King and Nicky Clark.
Rovers, meanwhile, were prevented from picking Light Blues teenager Ryan Hardie for the Ibrox fixture under the terms of his loan agreement.
Rangers started like they meant business as Jason Holt came close inside the opening 90 seconds while Forrester fizzed wide from 20 yards out.
Ray McKinnon's side, however, were not for lying down and gave the hosts a couple of scares with balls into Wes Foderingham's goalmouth.
But the breakthrough for the league leaders duly arrived after 27 minutes. Forrester's clever footwork sucked in Rovers midfielder Ryan McCord and he span clear before whipping an unstoppable effort over the head of keeper Kevin Cuthbert.
Warburton would have be slightly annoyed not to see his men further in front by the break but they resolved that complaint within six minutes of the restart.
King's jinking run from the left took him past three Raith players and the on-loan Hearts attacker looked up just in time to tee up Wallace arriving on the edge of the area. The Light Blues captain did not need a touch as he drilled a first-time shot under Cuthbert's body into the net.
Forrester's contribution to proceedings had been outstanding with his scheming from behind striker Clark central to Rangers' best moments. He was replaced by Dean Shiels on the hour mark, though, with Warburton keen to wrap the playmaker in cotton wool ahead of the cup duel with Paul Hartley's Dee outfit.
Holt almost netted a spectacular scissors kick but was denied by Cuthbert, who also pushed away a powerful King strike before Gers comfortably played out the final stages.