The 28-year-old has put pen to paper on a contract that will keep him at the Amex Stadium until 2015.
El-Abd came through the ranks at Brighton and made his first-team debut for the club in 2003.
He told Brighton's official website: "I'm absolutely delighted to have signed the new deal. I love playing for the club, and I can't wait for the season to start now.
"I've been keeping myself fit in the gym, and although it's not the same as doing pre-season, I feel really good and I'll definitely be fit for the start of the season.
"The last 10 years have been amazing, and I feel really honoured to have been granted a testimonial year by the club."
The centre-back made 34 appearances for the Championship side last season.