Newcastle United say manager Rafael Benitez will leave the club when his contract expires on 30 June.
The Magpies finished 13th in the Premier League last season as Spaniard Benitez, who took over in March 2016, secured the club's top-flight status.
"We have worked hard to extend Rafa's contract over a significant period of time," said a Newcastle statement.
"However, it has not been - and will not be - possible to reach an agreement with Rafa and his representatives."
The statement added: "The process to appoint a successor will now begin."
There has been continued speculation about his future prior to the club announcing his departure, with Benitez receiving a £12m-a-year offer to take over as manager at Chinese Super League club Dalian Yifang.
Former Valencia, Liverpool and Real Madrid boss Benitez's coaching staff of Paco de Míguel Moreno, Antonio Gomez Perez and Mikel Antia will also leave the club on 30 June.
Newcastle appointed Benitez as successor to Steve McClaren with the club one point from Premier League safety with 10 games left in the 2015-2016 campaign.
The 59-year-old could not prevent the St James' Park club from being relegated but they won the 2016-17 Championship title to secure an immediate return.
Newcastle finished 10th in their first season back in the Premier League and 13th last season.
"We would like to thank Rafa and his coaching team for their efforts over the last three years and their significant contribution to what has been collectively achieved," the statement added.
"We would also like to thank our supporters, players and staff for their patience during a period of uncertainty."
There has been talk of Newcastle owner Mike Ashley being in talks to sell the club to United Arab Emirates billionaire Sheikh Khaled bin Zayed Al Nahyan's investment group this summer.