[1] O'Hare started his acting career in 2002, appearing as Sean Weir in the Ultimate Force episode "The Killing of a One-Eyed Bookie".
In 2013, he appeared in the third season of the Western period drama Hell on Wheels, playing Declan Toole.
From 2016 to 2017, O'Hare voiced John Constantine in the superhero animated series Justice League Action.
[4] In 2017, O'Hare appeared as George Hall in the historical war family drama film Zoo.
From 2018 to 2019, he starred alongside Matt Ryan in the superhero action animated web series Constantine: City of Demons, voicing Chas Chandler.