Hall is Oxford's first signing since winning the play-off final
Promoted Oxford have signed former Luton midfielder Asa Hall on a two-year deal, while releasing four players.
Hall, 23, scored five goals in 33 Blue Square Premier appearances this season before being released last week.
Meanwhile, United have let go veteran goalkeeper Billy Turley, defender Kevin Sandwith, midfielder Chris Hargreaves and striker Francis Green.
Lewis Chalmers and John Grant have returned to parent club Aldershot, while Jamie Cook is transfer listed.
Turley, 36, Hargreaves, 38, and 30-year-old forward Cook, were the only United players who have played for them in the Football League - although the latter two have had spells away from United since then.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.