Matthias Groote was born on 21 October 1973 in Leer and went to secondary school in Westrhauderfehn, taking the leaving exam in 1990. He became an industrial engineer in 1995 and worked on plant design. In 1995 and 1996 he ran an alternate public service with the German Red Cross. He was a technical engineer in 1999, became a qualified industrial engineer in 2005, and also became a sales engineer in 2005.
Matthias Groote has been a member of the Ostrhauderfehn local council since 1996, a member of the Leer district council since 2001, and the chair of the Ostrhauderfehn SPD council group since 2001. He first became a member of the Social Democratic Party in 1996 and has been a member of the Leer SPD District Executive since 1997. He was chair of the Leer District Young Socialists from 1997 to 2002, vice-chair of the Weser-Ems District Young Socialists from 1999 to 2002, and has been a member of the Executive of the Weser-Ems Social-Democratic Association for Local Politics since 2003.