Achim Exner was born in Breslau on December 1, 1944.

He joined the SPD even before his university education. While studying economics at Johannes Gutenberg University in Mainz from 1967 to 1972, he continued to be politically active in the Hessian state capital.

After several years in the Wiesbaden city parliament, he was elected Lord Mayor by the city council in 1985. He was the last politician to be elected by the parliamentarians: since 1997, the citizens of Wiesbaden have voted directly for their city leader.

On the occasion of his retirement from office, he was honored for his services to the city by being entered in the Golden Book on September 18, 1997.