I want to thank him for his efforts and wish him the best for the future.Lee Bowyer
The 31-year-old joined Blues on a two-year deal in the summer of 2020 and went on to make 28 appearances in his first season at the Club.
Although the midfielder had 12-months remaining on his contract, both parties have agreed to conclude his time at the Club this summer.
Mikel San José commented: “This was not an easy decision for me. Although it was a difficult season for the team, I loved my time here and was privileged to play with my great teammates and staff.
“I feel now is the right time for me to explore another challenge and move on.
“My only regret is that I was not able to play in front of our fans, but I want to thank them for their support. The past year has been tough for everybody and I wish nothing but success for Birmingham City moving forward.”
Blues Head Coach, Lee Bowyer added: “When a player asks to leave then there’s no point having someone who is going to be unhappy at the Club. At that point, it’s clear that the best thing to do, for both parties, was to go our separate ways. I’d like to thank Mikel for all his hard work.
“Since I walked through the door he’s worked hard in training and when he played, he has done well for us. He helped us stay in the division, so I want to thank him for his efforts and wish him the best for the future.”