The 28-year-old has joined the Seagulls from Spanish side Almeria for a fee in the region of £1m, according to Sky sources.
Hemed scored eight goals in 26 La Liga appearances last season for Almeria but he unable to help them avoid relegation as a 3-2 defeat to Valencia on the final day of the season sealed their fate.
Hemed, who will wear the No 10 shirt for Albion, moved to Almeria on a free transfer last July, after a successful three-year stint at Mallorca.
The highlight of his Almeria career was a two-goal salvo against Malaga in January in a 2-1 win away from home, earning him the man-of-the-match award.
He had one year left on his current deal and has also plied his trade in Israel with Maccabi Haifa and Bnei Yehuda Tel Aviv.
Brighton manager Chris Hughton told the club’s official website: “Tomer is someone I have been aware of for a few years, and someone I watched a lot during my time at Norwich City.
“It was encouraging that when I first came to Brighton, Tomer was a player who Paul Winstanley and the club’s recruitment team were also aware of, and we have been working towards bringing him to the club since the start of the year.
“It’s been another great team effort from all key areas of the club to secure Tomer’s signature, and we are delighted to have completed the transfer and we welcome him to Brighton.
“Tomer is 6ft tall, strong, and he has played much of his football in La Liga and at international level. He is very capable of scoring goals.
“It’s another significant signing for us. I have no doubts about Tomer adapting to Championship football and improving our attacking threat.”