The 20-year-old has shone in the Premier League for the Seagulls this season since joining from Chelsea a year ago
Some of Europe’s biggest clubs were reported to be interested in signing him but he has signed a new deal with the Seagulls which runs until 2025.
Brighton manager Graham Potter told the club’s official website: “We are delighted to see Tariq commit his long-term future here.
“We knew his potential when we signed him a year ago, and hoped he would have a really positive impact on the club, and that has proved to be the case with his performances since June.
“He has been the model professional, he works exceptionally hard, is a humble lad and is a team player. He fits in with everything we would want from a player, now it’s about helping him reach his potential.”
Brighton’s gain has been Chelsea’s loss, despite Reece James making the right-back spot his own at Stamford Bridge.
The Seagulls swooped in the last January window to sign Lamptey for just £3 million, taking advantage of his expiring contract with the Blues.
On his new deal, Brighton’s technical director Dan Ashworth added: “It shows how well Tariq has adjusted to the demands of Premier League football.
“He fully deserves the new contract and has earned it with his hard work and performances.
“It now gives him and the club the opportunity to continue on the path he has started on since he joined last January.”
Lamptey missed Brighton’s 1-0 win over Leeds on Saturday with a hamstring injury that has kept him out of action since mid-December.