The arrangement frees Hemed to sign for the Championship club, and ends a four-year spell on the south coast.
Head coach Graham Potter said, “At this stage in his career Tomer wants to play regular football and at Charlton he has the opportunity to do that.
“There’s no doubt he’s been a great player for this club. He played an integral part in winning promotion from the Championship, and scored some crucial goals in the Premier League.
“During the short time I’ve been here, he’s been a fantastic professional. On behalf of the club I’d like to thank him for his service and wish him all the very best for his time with Charlton and his future career.”
Having started his career in Israel with Maccabi Haifa, before spells at Real Mallorca and Almeria in Spain, Hemed then moved to Albion in June 2015.
The forward netted his first goal for the club in a 2-1 victory against Fulham at Craven Cottage, which turned out to be one of 33 goals the striker scored in 108 appearances for the club.
His 17 goals in his debut season, including a hat-trick against Fulham in the reverse fixture, helped the Seagulls push for promotion, but defeat to Sheffield Wednesday in the play-offs ended those hopes.
However, the forward joined forces with the returning Glenn Murray and Sam Baldock to fire Albion into the Premier League in 2016/17 — hitting double figures (11 goals) for a second successive season.
Hemed found the back of the net in Albion’s first-ever Premier League victory — a 3-1 win against West Bromwich Albion — before scoring the winner in a 1-0 victory over Newcastle United a few weeks later.
The forward made 16 top-flight appearances for the club, before spending the 2018/19 campaign on loan at Queens Park Rangers, where he netted seven times.