Leeds began with what may be the team that starts against Millwall in eight days time, including the new centre-half pairing of Paul Butler and Sean Gregan.
Robbie Blake and David Healy gave the Tykes the runaround and Blake hit the bar early on before Healy opened the scoring.
The Irishman then turned provider after the hour mark, his cross finding Blake who headed in a second.
The hosts got on the scoresheet when striker Daniel Nardiello placed a low shot past Neil Sullivan, who played all the second half in goal.
Barnsley: Colgan, Vaughan, Burns, Hayes, Conlon, Austin, Kay, Wroe, Shuker, Tonge, Williams.
Subs: Carbon, Flinders, McPhail, Laight, Nardiello, Harban, Jarman, Joynes.
Leeds: Bennett (Sullivan h/t), Kelly, Butler, Gregan, Harding (Crainey 77), Wright, Bakke (Einarsson 70), Derry, Lewis, Healy, Blake.
Subs Unused: Kilgallon, Richardson, Morris.