[5] Brainfreeze was recorded by DJ Shadow and Cut Chemist as a practice session for a show in February 1999 at the Future Primitive Soundsession in San Francisco, mixing funk and soul 45's.

[9] This set was reenacted at the Mayan night club in Los Angeles on May 25, 2006, as part of a benefit concert for DJ Shadow's art director, Keith Tamashiro, in order to offset costs related to a brain aneurysm he suffered early in 2006.

Stanton Swihart of AllMusic stated that "Brainfreeze transforms the mix tape into a genuine piece of musical art, a sampladelic, turntablist collage that may be the apotheosis of – or at least a turning point for – the genre."

Describing the record as "an amazing display of spontaneous music-making", he concluded that "it is a dizzyingly brilliant, virtuoso work of two exceedingly fecund imaginations.

[16] Reviewing the duo's 2001 follow-up album Product Placement, Rob Mitchum of Pitchfork described Brainfreeze as "much admired" and said that DJ Shadow and Cut Chemist had "sculpted a mixtape symphony that withstood repeated listens".