The 24-year-old has turned out 152 times for the Seagulls since signing pro forms back in 2006 after coming through the club’s youth team.
A former player of the year, Elphick has been out with a serious Achilles injury and subsequently fallen behind Adam El Abd, Gordon Greer and Lewis Dunk in the centre back pecking order.
However he has been given a 12-month extension to his current deal.
Albion manager Gus Poyet told the club’s official website: “Tommy has had a very hard time with the injury but has shown great determination and is well on his way to a full recovery.
“With such intense competition for places throughout the squad, including the central defensive positions, that will be tough, but knowing Tommy he will be up for the challenge.”