Brunner received a Bachelor of Science degree in Industrial Design from San José State University in 1981.
After working as a designer and project manager at several high technology companies, Brunner went on to co-found Lunar Design in 1984. In 1989, Brunner accepted the position of Director of Industrial Design at Apple Computer, where he provided design and direction for all Apple product lines, including the PowerBook. He was succeeded by Jonathan Ive in 1997. Brunner claims that while with Apple, he hired Ive three times.
In January 1996, he became a partner in the San Francisco office of Pentagram. In 2006, Brunner partnered Alex Siow, founder of San Francisco-based Zephyr Ventilation, to launch outdoor grill design firm Fuego. Emblematic of his relationship with Siow, he designed the Arc Collection of modern range-hoods for Zephyr Ventilation.
By mid-2007 Brunner left Pentagram to start Ammunition Design Group. In 2008, former MetaDesign leaders Brett Wickens and Matt Rolandson joined Ammunition LLC as partners. In 2008, Brunner collaborated with Jimmy Iovine and Dr. Dre to launch Beats by Dre, and is responsible for the design of the company's lines of headphones and speakers including Beats Studio, Powerbeats, Mixr, Solo and Solo Pro as well as the Pill wireless speaker, among others. Brunner stepped down as Beats chief designer after it was acquired by Apple.
↑"Beats by Dr. Dre Beats Mixr". Industrial Designers Society of America – IDSA. June 4, 2012. Archived from the original on April 21, 2021. Retrieved April 19, 2021.