A Cleveland, OH native, Andreyko has been an active comics writer for numerous major companies such as DC and Marvel Comics. He is best known for his long run as the current writer of DC's ongoing Manhunter series in the 2000s.
Andreyko co-wrote the limited series Torso with popular 2000s comics writer Brian Michael Bendis, for which he was nominated a number of awards in 2003. He and Bendis are working with Paramount Pictures on a film adaptation of the work.
He co-created with P. Craig Russell, an Eisner- and Harvey-winning one-shot for Marvel Comics featuring Dr. Strange entitled What Is It That Disturbs You, Stephen?
In 1996, he directed a production of Joe Orton's Loot for the Weathervane Theater in Akron.
In 1997 he co-created The Lost, a Harvey-nominated comics mini-series which continued the story of Peter Pan in modern times, with the protagonist presented as an amoral vampiric boy prostitute.
He has written comics for other publishers, including IDW Publishing, and Todd McFarlane Productions/Image Comics.
In 2004, Andreyko began writing DC Comics' Manhunter series, relaunching it with a third volume--the character was originally conceived in the 1940s--in which he introduced the character of Kate Spencer and her supporting cast. He co-created (with artist Jesus Saiz) Kate Spencer, the title character of the series, the first female character to carry the long-running legacy. The series was canceled with issue #38 in January 2009, but the character has lived on and Andreyko continues to write a Manhunter back-up feature in DC Comics' Batman: Streets of Gotham monthly series that launched in June 2009.
Other recent work by Andreyko includes The Ferryman for Wildstorm, created by movie producer Joel Silver.