Middlesbrough in an official statement confirmed John Mikel Obi and two other players will leave the Riverside this summer.
Boro failed to qualify for a play-off spot in the Championship on the last match day losing their last qualification spot to Aston Villa.
Mikel Obi, 31, tore up his contract at Chinese Super League (CSL) side, Tianjin TEDA, after escaping relegation.
The Nigerian captain has battled injuries since the 2018 FIFA World Cup in Russia and has put in effort to get back in top shape. Towards the end of the season, Mikel was given the responsibility of captaining Tony Pulis side and he won three matches on the bounce for Middlesbrough.
The Super Eagles skipper recently announced his return to international football since Nigeria’s ouster at the Russia 2018 World Cup last summer.
Mikel is expected to lead the team to the 2019 AFCON tournament slated for Egypt, which would kick off on June, 21.
On the other hand, Middlesbrough have also released former England international Stewart Downing and former England U-21 goalkeeper Andrew Lonergan.
The 32-year-old midfielder spent the second half of the recently concluded season at Middlesbrough as they finished seventh on the Championship table after regular season.