After college, he worked as an exterior designer for Volkswagen, Mazda and General Motors.

[1] In 1997 he joined Mercedes-Benz as a transportation designer and became the manager for the exterior and interior styling of the R-Class, ML-Class and GL-Class models in 1999 and moving onto the A-Class, B-Class, C-Class, E-Class, CLK-Class and CLS-Class in 2002.

The following year he was promoted to Vice President Design of Daimler AG where he developed the company style called "sensual purity" in 2009.

[2] Wagener was appointed Daimler's Chief Design Officer in 2016, becoming a board member of the company.

Wagener was awarded the honorary title of Professor Honoris Causa from the Moholy-Nagy University of Art and Design in Budapest in 2009 and in 2010 he was awarded an honorary doctorate from the Technical University of Sofia.