His dating history has often been a topic of interest among fans. Foster has been linked to several high-profile relationships over the years, Ben Foster was in a relationship with German actress Antje Traue, his co-star in Pandorum. Traue revealed in an interview that she moved to Los Angeles and lived with Foster until their relationship ended around 2010. In early 2012, Foster began dating actress Robin Wright .
They became engaged in early 2014 but called off their engagement on November 12, 2014. The couple reconciled in early 2015 but announced their breakup again on August 29, 2015. In October 2016, Foster announced his engagement to actress Laura Prepon. Prepon gave birth to their daughter Ella in August 2017, and they married in June 2018.
Their son was born in February 2020. However, Foster filed for divorce from Prepon on November 12, 2024, citing “irreconcilable differences.” During custody proceedings, Prepon accused Foster of being an alcoholic. After filming Here, five cast and crew members got tattoos with the letters T.I.A., standing for "This is Armenia," as a tribute.