The moody Moroccan had sulked, bickered with his team-mates and asked to be substituted during the first half of the goalless draw at Hull on Saturday.
But the Rangers skipper was back to his best at Loftus Road as his 14th goal of the season helped sink Portsmouth.
Visiting goalkeeper Jamie Ashdown was at fault, though, after letting Taarabt's long-range drive slip through his hands.
Clint Hill headed the second to leave Neil Warnock's side five points clear at the top of the Championship.
Pompey, by contrast, are tumbling down the table after their winless streak was extended to eight games.
Yet they almost stunned the hosts inside the first 30 seconds after Bradley Orr felled David Nugent.
Liam Lawrence swung in the free-kick and Greg Halford had a free header but his effort was too close to Rangers keeper Paddy Kenny.
At the other end Taarabt fired wide from 25 yards before full-back Hill sent a rising drive over the crossbar.
Pompey threatened again midway through the first half when Dave Kitson jinked his way into the area and tried to dink the ball over Kenny, only to find the roof of the net.
With the visitors well on top, Matt Connolly earned himself a booking when he brought down Lawrence and Halford forced a fine save from Kenny with his fiercely-hit free-kick.
Then, from Lawrence's corner, Halford put his header narrowly over the top.
Rangers created their best chance of the opening half just before the break when Wayne Routledge teed up Alejandro Faurlin, whose curling shot was well saved by Jamie Ashdown.
At the start of the second half Taarabt embarked on a trademark mazy run, beating three players before finding Ishmael Miller who turned and fired narrowly wide.
And the breakthrough came in the 59th minute when Taarabt let fly again from outside the area and Ashdown fumbled the shot before turning in horror to see the ball bounce over the line.
Pompey attempted to hit back and Jonathan Hogg should have levelled when Kitson dummied Lawrence's cross into his path but the Aston Villa loanee put his effort wide.
And Rangers made the points safe in the 71st minute when Hill met Taarabt's corner with a towering header which gave Ashdown no chance.