The 23-year-old former Chelsea man is in line for his debut against Albion's promotion rivals Derby County at Craven Cottage on Saturday.
He will be ineligible to play against the Seagulls when the two sides meet at the Amex in April.
LATEST NEWS FROM SEAGULLS.CO.UK
Manager Chris Hughton commented, "After two seasons in which he has been a regular in the side, Rohan has found first-team opportunities limited this season, with Dale Stephens and Beram Kayal in such fine form, and also now following the arrival of Steve Sidwell.
"At his age and the stage he is at in his career, we want to see him playing regular football, and this loan move gives him the chance to do that in the Championship.
"It's a good move for Rohan and both clubs, as it is one which will allow him to continue the progress he has made in recent seasons."
Ince - who joined Albion from Chelsea in 2013 - has played 86 times for the club at senior level in the past three seasons, scoring four goals.
Last season he was runner up in the Football League's Goal of the Season Award for his stupendous volley at Swindon Town in the League Cup; and in 2013/14, in his breakthrough campaign, he was the club's Young Player of the Season.