In May 2015, his contract at Hamburger SV was terminated one year early by mutual agreement because he was not expected to feature in the next season.
He signed a three-year contract with 1.
FSV Mainz 05.

However at the start of the season, Beister suffered an injury on his knee and missed out throughout August.
Even after returning from injury, he remained out of the first team, due to competition in the midfield position.
Despite this, Beister made his only 1.
FSV Mainz 05 appearance, coming on as a substitute, in a 3–1 win against his former club, Hamburger SV on 5 December 2015.
In May 2015, his contract at Hamburger SV was terminated one year early by mutual agreement because he was not expected to feature in the next season. He signed a three-year contract with 1. FSV Mainz 05.
However at the start of the season, Beister suffered an injury on his knee and missed out throughout August. Even after returning from injury, he remained out of the first team, due to competition in the midfield position. Despite this, Beister made his only 1. FSV Mainz 05 appearance, coming on as a substitute, in a 3–1 win against his former club, Hamburger SV on 5 December 2015.
Maximilian Beister