Rothenberg was born to Gillian and Kenneth Rothenberg in Tenafly, New Jersey on June 20, 1975. He is of Jewish ancestry on his father's side and has two brothers and three sisters. In 2008, he revealed to People that, before turning to acting, he was a garbage man, a fact-checker for Mademoiselle, and a security guard. Rothenberg trained as an actor at the Acting Studio under James Price in New York City; while there, he performed numerous roles with Chelsea Repertory Company & LAB. From 1996 to 1997, he served in the United States Army, based in Germany.

At the Williamstown Theatre Festival, he starred as Doug in Alexandra Gersten-Vassilaros's Mother of Invention (2003), directed by Nicholas Martin, and as Lord Darlington in Lady Windermere's Fan (2005), directed by Moisés Kaufman. In 2011, he starred as Nils Krogstad in A Doll's House. Rothenberg then starred in the Mark Taper Forum's 2011 production of Burn This. Other theatre performances include Finder's Fee at the Edinburgh Fringe Festival, A Steady Rain, The Center of Gravity, Mad Forest, I'm Really Here and Almost Like Being.

Rothenberg has performed on television, in film and in theatre. In New York, Rothenberg has starred in many Off-Broadway productions. These include the lead in Second Stage Theatre's revival of Danny and the Deep Blue Sea (2004), as well as his critically acclaimed role in The Women's Project's Birdy (2003). In 2006, Rothenberg played the Scottish storyteller Chimney Bosch in the MCC Theater's The Wooden Breeks, directed by Trip Cullman. Outside of New York, Rothenberg starred opposite Patricia Clarkson as Stanley Kowalski in A Streetcar Named Desire at the Kennedy Center's Tennessee Williams Festival (2004).

In his television work, Rothenberg filmed one of the lead roles, Evan Wexler, in Fox's unaired television pilot Damages, and was also one of the leads, Eddie Caprio, in the comedy series Misconceptions, which also did not air. In 2008, he appeared as David "Augie" Augustine in the comedy-drama series The Ex List. Since 2012, he has had a starring role in the BBC One drama mystery television series Ripper Street, portraying Capt. Homer Jackson. In 2015, he was cast in the pilot of ABC's crime drama series Wicked City as Detective Jack Roth, an officer searching for a serial killer on the Sunset Strip. His role was recast in July 2015 after the show received its ABC airdate, and the role was instead given to Jeremy Sisto.