Firmino, who has scored 109 goals since his move from Hoffenheim in 2015, has won every major trophy with Liverpool including the Premier League, Champions League, FA Cup and League Cup.
The forward is out of contract at the end of the campaign and Liverpool boss Jurgen Klopp confirmed he was one of four players who would leave in the close season along with James Milner, Naby Keita and Alex Oxlade-Chamberlain.
"I am trying to focus on the game, but after it I will cry 100%," Firmino told reporters ahead of Saturday's game against Aston Villa, Liverpool's last home game of the season.
"I will miss everything - my teammates, the club, the fans, especially the fans. I love the fans, they've supported me a lot through these eight years.
"I am so proud of what we achieved here together. For everything that the club did for me and for my family, I'm so happy."
At his peak, Firmino was the fulcrum in Liverpool's three-pronged attack, forming a devastating partnership with Mohamed Salah and Sadio Mane.
But he has become a fringe player in the last two seasons and is no longer a guaranteed starter.
"It is time, unfortunately. The cycle here is ended and I understand it is time to go," he added.
"I'm very proud for everything that I have done here with the team, what we achieved together and the beautiful history we made together. Maybe one day I could come back, I don't know, but it's time to go."
