Taarabt, who left Spurs to join QPR two years ago, came back to haunt his former boss by curling home a wonderful first-half free-kick to put a severe dent in Tottenham's Champions League hopes.
The Moroccan lived up to his firebrand billing in the second half when he received a second booking for kicking the ball away.
Taarabt's actions will be forgotten by QPR boss Mark Hughes, though, as the forward's goal means his team are three points clear of the drop zone.
QPR thoroughly deserved their fourth successive home victory as they had more spirit, creativity and energy than a desperately lacklustre Spurs, who are now fifth in the Premier League table - three points behind Newcastle with only four games of the campaign left.
Harry Redknapp's team have now won just once in their last nine league games and their campaign looks set to end in failure.
Apart from the 12 minutes in which QPR had 10 men, a home win looked on the cards throughout and Rangers should have perhaps won by more.
The hosts stamped their authority on the game from kick-off.
Jamie Mackie in particular started brightly, taking the ball off Luka Modric and slipping past Benoit Assou-Ekotto and Gareth Bale before firing wide.
Tottenham, racked with nerves, played like anything but a top-four side in the opening 10 minutes.
Kyle Walker and Friedel were involved in a mix-up that almost gifted Rangers an easy opener.
They were also lacking going forward. After being out-muscled in midfield they had to resort to a long-ball game - something that was never going to work with the diminutive Jermain Defoe leading the line.
Samba Diakite made a mockery of the Spurs defence early on by coasting past Modric to slip in to the box but he dragged his shot wide.
Spurs momentarily came back in to the game with Paddy Kenny saving brilliantly from Bale and Rafael van der Vaart in quick succession, but their resurgence was short-lived as Rangers took the lead.
Mark Clattenburg blew for what appeared to be a handball against Sandro 25 yards out and Taarabt curled the ball over the wall and in to the bottom corner past a despondent Friedel, who perhaps should have done better.
Bale scooped a lovely ball over the QPR back four to find Defoe but Nedum Onuoha put in a crucial block as Spurs looked for an instant reply.
Van der Vaart rifled a half-volley at goal and Kenny's parry fell in to Defoe's path but he could only nod over.
QPR ended the first half on top.
Taarabt had time to subject Assou-Ekotto to a series of teasing step-overs on the touchline before the break and Joey Barton's deflected shot sailed over.
After seeing his team booed off by their own fans at half-time, Redknapp brought on Aaron Lennon for Sandro at to add a bit of width, but still Spurs struggled to get in to the game.
Diakite muscled his way past Scott Parker and William Gallas before burying a shot in to the side-netting.
Bobby Zamora wasted a good chance to seal the game in the 68th minute when Gallas allowed him room but the former Spurs striker dallied, allowing substitute Danny Rose to put in a crucial block.
Redknapp opted to switch Lennon and Bale - a move that went down terribly with the away fans, who sang: "Gareth Bale, he plays on the left."
Onuoha caught Parker's trailing leg, but Clattenburg waved play on. Barton insisted that Parker had dived to earn a free-kick and pushed the England captain.
Taarabt plunged his team's victory in to doubt with 12 minutes to go when he kicked the ball away to earn a second booking.
Modric stung Kenny's hands as Tottenham looked to use their numerical advantage and Redknapp brought on Giovani Dos Santos for Parker.
Anton Ferdinand headed Bale's cross away at the near post as Spurs piled on the pressure in the closing minutes.
Dos Santos drew a good save from Kenny in the final minute and Van der Vaart tested the stopper again in injury time.
Five minutes of added time were called but despite their best efforts Spurs could not find an equaliser and they ended the day outside the top four for the first time since November.