Rooney, younger brother of the England striker, spent six years at Everton's youth academy, before moving to Macclesfield Town for a further six years.
And after two years in the US with stints at MLS side New York Red Bulls and USL side Orlando City, he arrived at Oakwell last October but did not make a first-team appearance for the Tykes.
Other players released by the Championship side include Matt Done, centre-back Rob Edwards, and former captain Stephen Foster.
Foster joined Barnsley from Crewe in the summer of 2007 and has made over 220 appearances, scoring 10 goals, including a header in the famous FA Cup win at Liverpool in 2008.
Edwards, 30, joined the Tykes from Blackpool in 2011, but has been restricted to 17 first-team appearances and spent time on loan at Fleetwood and Shrewsbury this season.
Done, who followed former boss Keith Hill to Barnsley from Rochdale in the summer of 2011, spent the second half of this season on loan at Hibernian.
A number of players have also been offered new contracts, including England Under-21 international Martin Cranie, former Wigan midfielder Tomasz Cywka, and defender Bobby Hassell.
Tom Kennedy, Jimmy McNulty, Jason Scotland and Luke Steele have also been offered new deals with the club.