The squad is made up of a mixture of experienced players and youngsters who are still eligible for the national youth league team.
The squad will meet next week to start training, although O'Reilly will be looking to bolster his side with more players before the season starts in November.
As well as players from Dunedin, Queenstown and Invercargill footballers have been named to play in the squad.
During coming weeks, the new head coach will also be assessing a group of triallists, and confirming the availability of some players who have work, family and travel commitments pending.
O'Reilly wants Southern United players based in the region while representing the club, and said there was an opportunity for new players to break into the squad and make a positive impact in the coming season.
Trials for the national youth team will take place over the next few weeks.
