He is best known for his roles as Mickey Kostmayer on The Equalizer, Daniel Holtz on Angel, Gerard Stephens in The Dark Knight and Adam Engell in Argo.

His acting resume is extensive, appearing in numerous television programs including The Equalizer, Profit, The X-Files, Becker, Star Trek: Voyager, Star Trek: Enterprise, Charmed, Roswell, 24, Max Steel, The Inside, and Law & Order.

In 2016, he began the recurring guest role of Donatello Redfield in Supernatural, appearing in nine episodes before the show's conclusion in 2020.

Szarabajka has contributed his voice to several audio books, notably Fierce Invalids Home from Hot Climates by Tom Robbins, for which he won the 2001 Audie Award for Best Fiction, Unabridged; Fear Nothing and Seize the Night by Dean Koontz; several roles in a Grammy nominated audio dramatization of The Maltese Falcon,[3][4] Rising Sun by Michael Crichton; Nelson Algren's Walk on the Wild Side; and The Mark of Zorro opposite Val Kilmer.

Additionally, he provided the voice for antagonist Dmitri Yuriev in the Xenosaga series and for The Master of Whispers in the game Guild Wars: Nightfall and for Emile Dufraisne in Tom Clancy's Splinter Cell: Double Agent.

His most recent roles include the narrator Detective Herschel Biggs in the video game LA Noire, the Chaos Advisor and Captain Apollo Diomedes in Relic Entertainment's Dawn of War II: Chaos Rising, Warhammer 40,000: Dawn of War II – Retribution, Laserbeak in Transformers: Dark of the Moon, Bastion in X-Men Destiny, several voices in The Elder Scrolls V: Skyrim, Ronan the Accuser in The Avengers: Earth's Mightiest Heroes, the Living Laser in Ultimate Spider-Man, Azrael The Narrator in Darksiders, the Crowfather in Darksiders II, the Witch-king of Angmar in Guardians of Middle-earth, Russman in Call of Duty: Black Ops II, the Ur-Didact in Halo 4, General Spencer Mahad in Dead Space 3, and Cornelius Slate in BioShock Infinite.