Once again Keegan went with three up front in Obafemi Martins, Mark Viduka and skipper Michael Owens playing marginally behind the other two.
And the trio of attackers all got on the scoresheet to take their combined tally to eight goals in their last four unbeaten games.
Keegan felt one more win would be enough to save Newcastle's Premier League status and this result achieved that as United were rarely in trouble. They are now sitting pretty in 12th spot - just two points behind Carling Cup winners Spurs.
The only good news for Reading boss Steve Coppell was that with Bolton, Birmingham and Fulham all losing, they remain six points clear of the drop-zone with just five games remaining.
Stephen Hunt broke through the middle after 16 minutes only to be denied by an excellent Abdoulaye Faye tackle. And it proved to be a costly missed opportunity as Newcastle stormed in front within 60 seconds with only a third home goal of the season by Martins.
A wonderful pass from Nicky Butt picked out Martins on the left and he cut inside to add to his stunning strike at Spurs last weekend.
With their noses in front, Newcastle sprayed the ball about with purpose and should have doubled their tally on 37 minutes, Owen blasting the ball over the top from just six yards.
But Owen was not to be denied and made amends with a superb finish two minutes from the break having been presented with the opportunity by the hard-working Habib Beye.
Owen hooked the ball over Marcus Hahnemann to score for the fourth successive Premiership match, the first Newcastle player to do this since Alan Shearer in December 2003.
Keegan's ploy of playing three forward had Reading at times chasing shadows as was highlighted after 58 minutes when Beye enjoyed his second assist of the game as rampant Newcastle raced into a 3-0 lead.
Powering forward on the right, Beye received the ball from Viduka before cleverly picking out the big Aussie with a return pass and Viduka drove in from 12 yards.
Joey Barton had his best showing in a Newcastle shirt and twice went close late in the game before Hahnemann had to get his angles right to deny substitute Damien Duff.