Ehrenreich was born in 1989 in Los Angeles, California. His mother, Sari, is an interior designer and his step- father is an orthodontist. Ehrenreich attended Palisades Elementary School in Pacific Palisades, California and then Crossroads School in Santa Monica, California.
He lived in New York and studied theater at New York University. In 2009 he founded together with Zoe Worth the theater and film company The collectin.
He began his career with guest appearances on Supernatural and CSI: Crime Scene Investigation. After that he was seen in several short films before he played the role of Bennie in the independent film Tetro. In 2011, he starred in the horror film Twixt on the side of Val Kilmer.
In April 2012, he replaced Jack O'Connell in the role of Ethan Wate in the fantasy film Beautiful Creatures - An undying love, which started off in 2013 in the cinema. This role is his biggest success so far. Also in 2013, he has next to Nicole Kidman played the role of Taylor Whip in the horror film Stoker.
- 2006: Supernatural (TV series, episode 1x02 )
- 2007: CSI: Crime Scene Investigation ( CSI: Crime Scene Investigation, TV Series, episode 7x02 )
- 2009: Tetro
- 2011: Twixt
- 2013: Beautiful Creatures - An undying love ( Beautiful Creatures )
- 2013: Stoker
- 2013: Blue Jasmine