The Ibrox club have spent weeks in negotiations with Brighton over the transfer and the two sides finally appear to have come to an agreement.
Rangers will pay £3.5million for the centre-back who made three appearances for the Seagulls in the English Premier League last season.
The 25-year-old, who underwent heart surgery in 2017, is keen to join Steven Gerrard’s side as he seeks regular first-team football.
Meanwhile, Rangers are set to complete the signing of Ovie Ejaria from Liverpool on Wednesday.
The 20-year-old midfielder is expected to join the club for the duration of the 2017/18 season as he seeks to continue his development under Kop legend Gerrard.