The Swedish centre-back handed head coach Garry Monk a major boost by recovering from a hamstring strain suffered at Bristol City on Tuesday.
Jansson limped out of a 1-0 defeat at Ashton Gate after 45 minutes but retained his starting place this afternoon as Monk named an unchanged side for the third game running.
Liam Bridcutt, however, was missing again after Leeds ruled their captain out for up to eight weeks with a fractured foot this week. Youngster Ronaldo Vieira was back on the bench after a recent knee problem.
Barnsley, who sacked assistant boss Tommy Wright on Thursday following revelations about him in the Daily Telegraph, made three changes after a midweek draw with Aston Villa, promoting Sam Winnall, Adam Hammill and Adam Armstrong to their starting line-up.
Leeds United: Green, Ayling, Bartley, Jansson, Taylor, O’Kane, Phillips, Sacko, Hernandez, Dallas, Wood. Subs: Silvestri, Coyle, Cooper, Vieira, Mowatt, Roofe, Antonsson.
Barnsley: Davies, Yiadom, Roberts, MacDonald, Kpekawa, Hourihane, Hammill, Kent, Winnall, Armstrong. Subs: Townsend, Jackson, White, Watkins, Lee, Morsy, Bradshaw.