Sinnreich currently serves as Director at OMD Ignition Factory, where he runs a unit of the major media agency's innovation lab. He is also an Adjunct Professor at New York University's department of Media, Communication and Culture, where he was previously employed as full-time faculty (2007-2009). Previously, Sinnreich served as Managing Partner of Radar Research, a media and technology consultancy based in Los Angeles (2005-2009), and as Senior Analyst at Jupiter Research in New York, where he managed the units related to digital music and communications policy (1997-2002). He has written about music and the media industry for publications including The New York Times, Billboard, Wired News, Truthdig and American Quarterly, and his first book, Mashed Up: Music, Technology and the Rise of Configurable Culture, is due to be published by University of Massachusetts Press in 2010.

Sinnreich has appeared on ABC World News Tonight, The CBS Early Show with Bryant Gumbel, NBC's Today Show, CNN, CNBC, BBC Radio and Fuji TV. He has also addressed several university audiences and professional organizations, including Fordham University, University of Amsterdam, Technical University of Munich, and The New York State Bar Association. He has also served as an expert witness in several court cases, including the recent Supreme Court file sharing suit MGM v. Grokster.

Sinnreich also writes and performs music, as bassist for artists and groups including seminal ska-punk band Agent 99 (Shanachie Records) dancehall reggae queen Ari-Up (lead singer of The Slits), and Tony award-winner Trazana Beverly, and as a co-founder of NYC soul group Brave New Girl and LA dub-and-bass band Dubistry. Two of the songs he composed for Brave New Girl have been licensed to MTV's animated series, Daria, and a song he wrote for Dubistry was featured in the award-winning short film Life As You Know It, directed by Kristina Robbins-Higgins for Audi Films.

Sinnreich holds a B.A. in English from Wesleyan University, an M.S. in Journalism from Columbia University, and an M.A. and Ph.D. in Communication from the Annenberg School for Communication at the University of Southern California.