Young defender Haydon Roberts has signed a new three-year contract with the club until 2023.
The 18-year-old also completed a loan move to League One side Rochdale, ahead of last Friday's transfer deadline.
Technical director Dan Ashworth said, “This is a great opportunity for Haydon to go and play regular football at a relatively young age.
“He has been on the fringes of our first team for a while, and regularly trains with Graham Potter and the senior players.
“He has demonstrated his undoubted potential in the cup matches he has played this season and last, and now has an appetite to play regular senior football.
“This move is one which is ideal for his development and we feel will really benefit him.
“David Weir and the loans team will monitor his progress over the coming weeks and reassess in January.”
Brighton-born Roberts joined Albion as a schoolboy, and has graduated through the club’s academy pathway.
He has also represented England at all levels from under-16 to under-19.
His first-team debut came in last season’s Carabao Cup tie against Aston Villa, and he featured in matches against Portsmouth and Preston North End this season.