Royo was born in the Bronx, New York of African American and Cuban heritage. Allegedly, Royo has often been told by casting directors that he is "not black enough" or "not Latino enough" for certain parts.

Royo attended Mount Saint Michael Academy in The Bronx from 1982 - 1986 at the same time as Sean Combs.

He had a small role in John Singleton's 2000 remake of the film Shaft. He had a brief appearance in Terminator: The Sarah Connor Chronicles as a soldier in a unit that was sent back in time. He has also had roles in Heroes and Kenan and Kel.

He is mostly known for his starring role on the HBO program The Wire as drug addict and confidential informant "Bubbles" since the show's first season. He also appeared in the 2005 movie G, which was based on The Great Gatsby.

He was introduced as the character Stephen Canfield during the third season of the television series Heroes. He also played the role of a drug addicted homeless serial killer in the Criminal Minds Season 4 episode "Catching Out".

Royo was also featured at a Harvard University panel discussion in October, 2009, along with fellow actors from The Wire, Sonja Sohn and Michael K. Williams. The panel discussed the value of The Wire as a media source at-risk youth can relate to and learn positive life lessons from.

In 2010, Royo guest starred on the Starz original series Party Down.

Royo is married with a daughter, Stella.