The club have confirmed Hall will move on when his contract expires at the end of the 2018 campaign.
Rhinos’ announcement paves the way for Australian NRL club Sydney Roosters to confirm Hall’s signing on a deal beginning next year.
Hall is the fifth-highest try scorer in Leeds’ history, with 231 touchdowns in 327 games and will leave big boots to fill.
“He has been a brilliant servant to the club and I’m disappointed to see him go, but I fully understand it,” said Rhinos’ director of rugby Kevin Sinfield who played alongside Hall in five of the winger’s six Grand Final wins.
“There’s a couple of wingers we have talked about and discussed.
“Ideally we would bring someone through from our system, but when you’re talking about someone of the calibre of Ryan Hall it is a big decision to make.
“We will be looking to strengthen the whole group for 2019 and beyond with this opportunity.”
Ash Handley, who had been understudy to Hall and Leeds’ other first-choice winger Tom Briscoe, signed a long-term contract last month, but has established himself in the centres this season.
Rhinos signed Briscoe’s brother Luke from Featherstone Rovers, where he is currently playing on dual-registration, when Hall was unavailable due to England duty in June.
Rovers are keen to keep Luke Briscoe, but he is likely to be among the contenders to fill the vacancy.
Hall turned down the offer of a new contract, but insisted his decision to leave was not due to issues with his hometown club.
In a statement released by Rhinos, Hall said: “I have had 12 amazing seasons as a Leeds Rhinos player and I am immensely proud of what we have achieved together.
“For me personally, I feel that this is the right time for a new challenge after such a long period at the club and my decision in no way reflects on the Rhinos.”
He added: “Words cannot really do justice to how much representing my hometown club and enjoying so much success has meant to me.
“My focus now is on the remainder of this season and putting the Rhinos in the best possible position for next season and beyond.
“I have had the privilege of working with brilliant coaches and players in my time at the club and I have total faith that under Kevin Sinfield and James Lowes the club will continue to go in the right direction for the future.”
Sinfield added: “The club were keen to keep him and we made him an offer that reflected his standing in the game.
“I know Ryan will be doing everything between now and the end of the season to make sure his time at the club ends on the best possible note.
“He will remain a close friend of the Rhinos. As a Leeds lad, playing for his club and winning with the Rhinos means so much to him and I am sure we will remain in regular contact with him.”
Hall has won the Challenge Cup twice with Leeds and was man of the match at Wembley in 2014.
He was a try scorer in the 2012 World Club Challenge win over Manly Sea Eagles and his last-gasp touchdown at Huddersfield Giants in 2015 secured the league leaders’ shield.
He has also touched down 35 times in 38 Tests for England.