is an American professional soccer player who plays as a center-back for Major League Soccer club Nashville SC and the United States national team.

A native of Lawrenceville, Georgia, Zimmerman played two seasons in college with the Furman Paladins before signing a Generation Adidas deal with Major League Soccer. He was then selected in the 2013 MLS SuperDraft by FC Dallas as the 7th overall pick. Initially struggling for playtime due to injuries, Zimmerman established himself as a regular starter in 2016. He started in 38 matches as FC Dallas completed the double, winning the Supporters' Shield and the U.S. Open Cup. In December 2017, Zimmerman was traded to expansion side Los Angeles FC, helping the club win the Supporters' Shield in 2019. Zimmerman was also selected for the MLS All-Star team and MLS Best XI. Zimmerman was then traded to another expansion side, Nashville SC, in February 2020. With Nashville, he won back-to-back Defender of the Year awards in 2020 and 2021.

Zimmerman made his debut for the United States in January 2017 against Jamaica. In 2019, he was selected into the squad that finished runners-up in the CONCACAF Gold Cup. He was also a member of the squad that won the tournament in 2021, starting all three group stage matches before having to leave the tournament due to a hamstring injury.