Bethel made his on-screen debut as Brad in the teen drama series The O.C., in the episode "The Telenovela". He had guest roles in JAG, Cold Case, and NCIS, and portrayed Corporal Evan "Q-Tip" Stafford in the Emmy-nominated mini-series Generation Kill, starring Alexander Skarsgård. Bethel made his film debut in the 2008 Vietnam War film, 1968 Tunnel Rats where he played the Army Special Ops soldier, Corporal Green. In 2009, he landed a recurring role as Ryder Callahan on the CBS daytime soap opera The Young and the Restless.
In The CW's comedy-drama series Hart of Dixie, Bethel played Wade Kinsella, "bad-boy" neighbor to the series' central character, Zoe Hart. Production for the show began in early 2011 and it premiered on September 26, 2011. The series concluded on May 7, 2015, after four seasons. BuddyTV ranked him #14 on its list of "TV's Sexiest Men of 2011"; in 2012 he was ranked #2 on the same list. He appeared in four episodes of ABC's legal thriller series How to Get Away with Murder as Charles Mahoney.
In 2017, he joined the Roundabout Theatre Company's production of The Last Match, which was set in the world of professional tennis. In 2018, he joined the cast of Daredevil as Benjamin "Dex" Poindexter, also known as Bullseye and reprised the role in Daredevil: Born Again (2025–present). In 2019, Bethel landed a main role on the CBS legal drama series All Rise as Deputy District Attorney Mark Callan.
