Six thousand Wolves fans, who had already turned Oakwell into a giant party, turned up the volume again to celebrate.
But if the fans were in fine voice then the players struck the wrong chord with manager Mick McCarthy as the former Barnsley starwas earlier fuming on the touchline
Still requiring a point to confirm the Championship title they were second best to a Barnsley outfit desperate for a win to help them avoid the drop to League One.
Winger Adam Hammill saw an early 25-yard free-kick deflected wide.
Jamal Campbell-Ryce's raking shot was spilled by keeper Wayne Hennessey and Wolves managed to scramble away as Jon Macken tried to force the ball in.
And when Bobby Hassell smashed a free-kick there was another scare as Hennessey collided with skipper Jody Craddock and dropped the ball.
Anderson Silva scooped a shot over from 15 yard out after another Hassell free-kick caused havoc.
And Hennessey had to be alert when as pass from Daniel Bogdanovic found Macken but the keeper snatched away the chance.
Wolves, who looked jaded with promotion already confirmed, hardly had a look at the home goal and a Dave Edwards shot which flashed well wide with their best first-half effort.
Wolves started brighter in the second half and sub Sam Vokes might have seized on a chance but for Hassell.
But Barnsley continued to search for a goal and it came after 58 minutes when a mis-hit ball from Daniel Bogdanovic broke for Macken.
When his hurried shot was blocked, the experienced striker pounced and rifled in the shot at the second attempt.
Vokes might have levelled but for a super point-blank save from Luke Steele and Vokes pounced on a mistake by Darren Moore but his shot was off target.
But Wolves levelled in the 79th minute when Matt Jarvis darted down the left and produced a dangerous cross which Reid rifled home in front of the ecstatic Wolves fans.