Danny Wilson is the new Barnsley manager and his assistant will be former caretaker Micky Mellon.
The club have refused to say how long Wilson, who led the Reds to the Premier League in 1997 and left the following year, is contracted for. Mellon had been in charge of the side since David Flitcroft was sacked on November 30.
Wilson, 53, took over from Viv Anderson as Barnsley manager in 1994 and took them to the top flight for the 1997-98 campaign before leaving for Sheffield Wednesday.
He then spent four seasons at Bristol City before managing MK Dons, Hartlepool, Swindon Town and Sheffield United, who he led to the League One play-off finals in 2012 before being sacked earlier this year.