Keating first came to major public attention in the UK when he had a semi-regular role as Tony in the Channel 4 sitcom Desmond's (1989–95). He went on from this to a role in Inspector Morse, as well as other guest-starring roles.
Having moved to the United States, he gained the role of the demonic warrior Mallos on the short-lived 2000 series The Immortal. He starred in the Zalman King series chromiumblue.com. He also made guest appearances on Buffy The Vampire Slayer, G vs E and Special Unit 2 as well as on several other series prior to a major role on the series Star Trek: Enterprise, where he played Lieutenant Malcolm Reed. Since then he has had a guest roles on the series Las Vegas, Holby City and the CSI: NY episode "Uncertainty Rules".
Keating joined the cast of hit show Heroes for its second season and played an Irish mobster in a four episode arc. He also held a guest-starring role for three episodes on the Fox TV series Prison Break.