In March 2013, Brolin began dating his former assistant and model Kathryn Boyd. They became engaged in March 2015. The couple married on September 24, 2016, and announced on May 29, 2018, that they were expecting their first child. Brolin announced through Instagram on November 4, 2018, that Boyd had given birth to a daughter. Their second daughter was born on December 25, 2020.
