Pablo Tell Schreiber was born in Ymir, British Columbia, Canada, to Lorraine Reaveley, a Canadian psychotherapist, and Tell Schreiber, an American actor. His paternal half-brother is actor Liev Schreiber. Pablo, who is named after Chilean poet Pablo Neruda, was raised in Ymir, and moved to Seattle, Washington, as a teenager.

Pablo Schreiber was nominated for a Tony Award for his Broadway debut performance in the revival of Clifford Odets' classic Awake and Sing! directed by Bartlett Sher.

Schreiber has appeared in many films, including: Josh Radnor's Happythankyoumoreplease (2010), which won the Audience Award at Sundance, Vicky Cristina Barcelona (2008), Lords of Dogtown (2005), Tell-Tale (2009), Nights in Rodanthe (2008), The Manchurian Candidate (2004), Recalled (2012), Breaking Upwards (2009), Into the Fire (2005), The Mudge Boy (2003) and Invitation to a Suicide (2004). Upcoming he appears in the independent features Fort Bliss (2014), The Dramatics: A Comedy (2015) and Preservation (2014).

Television credits include his classic role as "Nick Sobotka" in HBO's critically acclaimed The Wire (2002); and most recently as the menacing villain "William Lewis" on Law & Order: Special Victims Unit (1999), NBC's "Ironside" and as "Pornstache" in Jenji Kohan's hit series Orange Is the New Black (2013). He's also appeared in Stephen Frears' Muhammad Ali's Greatest Fight (2013) for HBO and on Weeds (2005), A Gifted Man (2011), Lights Out (2011), The Good Wife (2009), White Collar (2009), The Beast (2009), Life on Mars (2008), It's Always Sunny in Philadelphia (2005), Fear Itself (2008), Dirt (2007), John Grisham's A Painted House (2003), Law & Order (1990), Law & Order: Criminal Intent (2001), and The Black Donnellys (2007).

Schreiber has performed in numerous Broadway and off-Broadway plays including: Desire Under the Elms on Broadway directed by Robert Falls, Rajiv Joseph's Gruesome Playground Injuries at Second Stage, Neil LaBute's Reasons to be Pretty at MCC (for which he won the Drama Desk Award), Dying City at Lincoln Center, Mr. Marmalade at Roundabout, Sin: A Cardinal Deposed at The New Group, Manuscript at the Daryl Roth Theatre, Julius Caesar at the New York Shakespeare Festival, and Blood Orange, his professional debut.