He is the founder and CEO of Blumhouse Productions, which has produced the horror franchises Paranormal Activity (2007–2021), Insidious (2010–2023), The Purge (2013–2021), and Halloween (2018–2022).

[4] He received the Primetime Emmy Award for Outstanding Television Movie for producing the drama film The Normal Heart (2014).

[11][12] Blum worked for Bob and Harvey Weinstein as an executive at Miramax, and later as an independent producer for Paramount Pictures.

Prior to his tenure at Miramax, Blum was a producing director at Ethan Hawke's Malaparte theater company.

[14] He obtained financing for his first film as producer, Kicking and Screaming (1995), after receiving a letter from family acquaintance, entertainer Steve Martin, who endorsed the script.

[15] In 2000, he founded Blumhouse Productions, which specializes in producing micro-budget movies that give directors full creative control over the projects.

[24][25] On August 14, 2020, Daily Front Row listed Blum as one of a group of high-profile investors who purchased W, a troubled fashion magazine.

[28] Blum is on the Board of The Public Theater in New York, the Sundance Institute, Vassar College, and the Academy Museum of Motion Pictures.