Willian has netted 44 goals in 236 appearances for the Blues since joining in 2013.
The Sun, UK, reports that the forward may have played his last match for the Blues.
Former Blues’ manager, Antonio Conte and Willian fell out towards the end of the Italian’s tenure at Chelsea.
The forward aimed a swipe at the Italian following the club’s FA Cup win in May.
There were hopes at Chelsea that Willian could be tempted to stay on after Conte’s departure but, according to the newspaper, the Brazilian has decided to leave.
Manchester United and Barcelona are keen on Willian and The Sun claimed the attacker was discussing a possible move to the Nou Camp with Philippe Coutinho at the World Cup.
Willian is desperate to play Champions League football next season, which both United and Barca are able to provide
Chelsea will play in the Europa League next season after finishing outside the Premier League top four.