Best's first goal since September ensured Mark Hughes' first game as QPR boss ended in narrow defeat.
The Republic of Ireland striker took his tally for the campaign to four with a neat finish eight minutes before the break to win a fiercely-contested game.
Rangers had more than enough chances to get something out of the contest after creating a host of chances which were either squandered or repelled by goalkeeper Tim Krul on an afternoon when the Magpies turned in an unconvincing performance against the 18th-placed visitors.
However, Alan Pardew's men, who lost key midfielder Yohan Cabaye to a worrying ankle injury in the first half, just about did enough to emerge with the points after claiming a fourth win in five games in all competitions in front of a crowd of 49,865.
Hughes arrived on Tyneside having inherited a side which had not won in nine games in all competitions and had taken just two of the last 24 points on offer, and faced the task of overcoming a team which had comprehensively beaten champions Manchester United last time out.
However, the early signs were positive, even without suspended skipper and former Magpies Joey Barton, the injured Alejandro Faurlin and African Nations Cup absentees Armand Traore and Adel Taarabt.
QPR enjoyed much the better of the opening stages with Krul saving from Heidar Helguson and Akos Buzsaky inside the opening six minutes.
Newcastle were unable to get out of their own half and with wide men Shaun Wright-Phillips and Jamie Mackie forcing a series of errors from full-backs Danny Simpson and Davide Santon, Krul's goal came under repeated threat.
Indeed, Wright-Phillips clipped the crossbar after capitalising on a 16th-minute mistake by Simpson to leave the home fans less than impressed.
However, the flow of the game was to change as the game reached the 20-minute mark, and it did so as Cabaye, whose central midfield partnership with Cheick Tiote has been one of the features of the Magpies' season to date, left the field on a stretcher with what looked like a nasty ankle injury after an uncompromising challenge by Shaun Derry.
Even as Pardew urged Hatem Ben Arfa to hurry up on the sidelines to replace his compatriot, the 10 men responded to finally pin the visitors back.
Ben Arfa, whose stunning strike last weekend revived the Magpies' FA Cup campaign, eventually emerged from the dugout to warm applause, although Krul was sent sprawling across his line when Jay Bothroyd curled a 33rd-minute effort just wide.
But Ryan Taylor forced a fingertip save from Paddy Kenny seconds later as the home side belatedly built up a head of steam.
They made the pressure tell eight minutes before the break in impressive style.
Jonas Gutierrez set off towards the penalty area to feed striker Shola Ameobi, who laid the ball off to Taylor.
The midfielder managed to stab a pass out to Best before the covering tackle arrived and the frontman stepped inside full-back Luke Young before side-footing calmly into the far corner to end a four-month wait for a goal.
Hughes' men left the field at the break having given a decent account of themselves, but with Clint Hill and Bothroyd having joined Derry in referee Chris Foy's notebook as their physical approach took its toll.
But they resumed in promising fashion with Wright-Phillips testing Krul from distance within two minutes after Bothroyd had headed down Hill's long-ball to him.
They could have been back on terms twice within as many minutes with Bothroyd blasting wastefully over from Helguson's knockdown and then forcing a solid save from Krul after being played in by Mackie.
However, Santon might have extended the home side's lead had it not been for a fine 55th-minute block by Young after the full-back had carved his way into the box from the left.
Newcastle were disjointed but they almost wrapped up the points with 17 minutes remaining when Ben Arfa slid the ball into Best's path. However, when he squared towards Ameobi, Hill just managed to get a touch to deny the striker a simple finish.