Gert-Uwe Mende was born in Bonn in 1962; from 1966 he grew up in Bebra in northern Hesse. After completing his studies in Göttingen, majoring in medieval and modern history and minoring in political science and economics with a Magister Artium degree in 1987, Gert-Uwe Mende did his civilian service at the student union in Göttingen.

This was followed by an editorial traineeship at the Hessische Niedersächsische Allgemeine (HNA) in Kassel and editorial work in the news/politics department. On July 1, 1991, Gert-Uwe Mende became press spokesman for the Hessian Minister of the Interior, Dr. Herbert Günther, and remained so from 1994 under his successor Gerhard Bökel. From 1997 to 1999, he headed the minister's office. From May 1999 to 2006, Gert-Uwe Mende was press spokesman for the SPD parliamentary group in the state parliament and from May 2006 until the end he was managing director of the SPD parliamentary group in the state parliament.

Gert-Uwe Mende joined the SPD in 1979. Until his election as mayor of Wiesbaden, he was deputy chairman of the Wiesbaden SPD sub-district and has been a member of the Wiesbaden-Dotzheim local advisory council since 2016, most recently as local chairman since August 2018.

Gert-Uwe Mende is married and has two grown-up children.