The 22-year-old will be immediately loaned back to the Rocks, where he has formed a vital partnership with fellow-O's loanee Michael Clark.
Ekpiteta started his career at Oxford United and has had spells at Chelmsford City and Concord Rangers before joining John Coventry's side, making over 100 appearances in the process.
The 6`4” defender is the Rocks' leading appearance maker this season and has signed a two-and-a-half-year deal at Brisbane Road.