The following year Bierko transferred to Northwestern University to study acting alongside David Schwimmer, Stephen Colbert, George Newbern and Harry Lennix.

Bierko appeared for four seasons in the Peabody Award-winning series UnREAL as Chet Wilton, the eccentric, drug addicted, womanizing creator of a reality dating show.

[8] Recently, he appeared on The Blacklist as The Chairman, the coldly sociopathic head of an underground stock market for criminals, and was seen on season two of the hit Netflix show Sex/Life as a superstar literary agent.

In 2000, Bierko made his Broadway debut as Professor Harold Hill in Susan Stroman's critically acclaimed revival of Meredith Willson’s The Music Man, for which he received a Tony Award nomination.

[13] In 2022, Conor McPherson cast Bierko as Mr. Burke in his Girl from the North Country (featuring music by Bob Dylan) opposite Luba Mason and Mare Winningham.