On-loan midfielder Paul Wotton has returned to Southampton while Dannie Bulman has also left Oxford and joined Crawley.
Wotton has returned to parent club Southampton following a successful loan spell in which he played four times and Bulman has joined former club Crawley Town on a permanent deal.
Boss Chris Wilder told the club's official website: "I would like to thank Paul for his excellent contribution to this club.
"His attitude towards the club was exceptional and he played a very important part in getting the club back on the right track.
"Dannie was a good player at Oxford and he was a key figure last season in getting the club promoted.
"I would like to thank Dannie for his efforts and I wish him all the best for the future."