He was subsequently drafted seventh overall by FC Dallas in the 2013 MLS SuperDraft. Overcoming early injury challenges, Zimmerman quickly established himself as a formidable defender, playing a pivotal role in FC Dallas’s victory in both the Supporters’ Shield and the U.S. Open Cup in 2016. In December 2017, Zimmerman was traded to expansion side Los Angeles FC, where his strong defensive skills helped the team secure the Supporters’ Shield in 2019.
Recognizing his invaluable contributions and leadership, Nashville SC signed Zimmerman to a notable contract extension through 2025 in 2022, securing his status as a Designated Playera significant milestone for an American defender in MLS history. He remains a central figure for both club and country, celebrated for his defensive strength and on-field leadership.