The 25-year-old informed his teammates at the start of a training session, which coach Ernesto Valverde gave the Brazilian permission to miss in order to resolve his future.
The announcement comes amid mounting speculation Neymar is set to join Paris Saint-Germain in a world-record deal.
“The player Neymar Jr, accompanied by his father and agent, has informed FC Barcelona this morning of his decision to leave the club in a meeting held at the club’s offices,” read a statement from Barcelona.
“Faced with this position, the club has informed them they refer to the buy-out clause of his existing contract which as of 1 July totals 222 million euros (approximately $262M) which will have to be deposited in its entirety.
“Furthermore, in reply to the claim for the contract extension bonus, the club has once again made it clear that the amount remains deposited with a notary until the case is resolved.
“The player remains under contract at FC Barcelona but with temporary permission to not take part in training sessions.”
Marcelo Bechler, the Brazilian journalist who first reported the expected transfer back in July, told CNN Neymar’s decision to move is born out of the desire to one day be crowned the world’s best footballer.
“Neymar thinks he can be the best player in the world,” Bechler said. “And it cannot happen if he plays with (Lionel) Messi.
“They are friends but Neymar can’t play with Messi and be the best player in the world, so that’s why he’s made the decision to leave Barcelona.”
In response to Neymar’s likely departure, his teammate and “friend” Messi posted an emotional farewell video on Instagram.
“It was an enormous pleasure to have shared all these years with you, my friend,” the Argentine wrote. “I wish you lots of luck in this new chapter of your life.
“See you, I love you a lot.”
As one third of a feared triumvirate alongside Messi and Luis Suarez, Neymar has scored over 100 goals for the Catalan club, helping them win the Champions League, two La Liga titles and three Copa del Reys since his arrival in 2013.
He signed a new five-year deal with Barcelona in 2016.