Barnsley hardly knew what had hit them after keeper Luke Steele was red carded just before half-time and Peter Lovenkrands fired Newcastle ahead from the spot.
The second half was a rout as Lovenkrands doubled his tally, Danny Guthrie bagged a couple and they were joined on the scoresheet by Kevin Nolan and Jonas Gutierrez with Daniel Bogdanovic getting a late consolation for the visitors.
United are now eight points clear of Nottingham Forest after West Brom were beaten at QPR and next up, it's a derby date on Teesside with Middlesbrough.
Lovenkrands had the ball in the net after just six minutes but was caught marginally offside.
Emil Halfredsson managed Barnsley's only worthwhile first half effort but his shot from a tight angle was comfortably dealt with by Steve Harper.
Andy Carroll headed a Fabrice Pancrate cross back across goal and narrowly wide as United upped the tempo.
Defender Bobby Hassell was perfectly position to head a Danny Simpson shot over the bar, before the Magpies broke the deadlock on the stroke of half-time when Lovenkrands scored for the third successive home game.
Put through by Pancrate, the Dane was pulled down by keeper Luke Steele. Referee Grant Hegley pointed straight to the spot and despite his protests showed the keeper a straight red card.
David Preece was sent on as reserve keeper for Anderson De Silva and his first job was to pick the ball out of the net after being sent the wrong way by Lovenkrands.
With five minutes of the second half, the 10-men of Barnsley trailed 3-0 as Lovenkrands again and Guthrie tore them to shreds.
Carroll's superb ball from the left was headed in by Lovenkrands before the Dane switched from goalscorer to goal-maker when he teed up Guthrie to drive in from 30 yards.
The Spiderman mask finally made its appearance when Gutierrez scored a stunning solo effort on the hour mark.
The Argentine received the ball wide on the left before driving inside and letting fly with a 25-yarder that flew into the net off the underside of the bar and Gutierrez donned the superhero's mask as he celebrated with the crowd.
It got even better after 69 minutes when Guthie claimed his second as his 35-yard free-kick into the danger area evaded everyone as it ended up in the net.
The floodgates opened again after 71 minutes when Nolan made it 13 for the season when he waltzed through to sidestep Preece and make it 6-0.
Only the woodwork denied Lovenkrands a second home hat-trick of the season his glancing header from Gutierrez's cross cannoning off the upright and dropped into the arms of Preece.
Pancrate then broke clear but fired wide with only Preece to beat and, with seven minutes to go, a defensive lapse let in Barnsley substitute Bogdanovic for his 11th of the season.