Sargent researched and taught psychology at the University of Cambridge. He started playing Dungeons & Dragons in 1978 through friends. TSR UK were based in Cambridge, and they met with Sargent after he had submitted an article to Imagine magazine. The TSR UK crew later left to work for Games Workshop. He later worked as a freelance designer, and was brought in by TSR to work on Greyhawk.

Most of Sargent's role-playing works were published between 1987 and 1996. He has authored many products for both the Dungeons & Dragons (particularly for the World of Greyhawk campaign setting), "Warhammer Fantasy Roleplay", and FASA's Shadowrun and "Earthdawn" role-playing games (most of the latter in collaboration with Marc Gascoigne). He also authored various Fighting Fantasy gamebooks and novels, some under the pseudonym Keith Martin , and some Sonic the Hedgehog novels under the collective pseudonym Martin Adams (with Gascoigne and James Wallis) . Sargent's work into ESP has come under considerable criticism in relation to fraud, from that of Blackmore (1987) to that of Bem and Honorton's review (1994), in which continuous allegations of suspicious activity occur.

According to Sean K Reynolds, Carl Sargent was in a serious car accident and suffered major injuries. He's basically unable to work because of the long-term effects of those injuries.

Sargent holds a PhD in psychology (or experimental parapsychology), which he earned in 1979. He is known to have performed numerous ganzfeld experiments at the University of Cambridge (a photograph of Sargent performing such an experiment appears in the Encyclopedia of Pseudoscience, page 129). His published works in this field include Explaining the Unexplained: Mysteries of the Paranormal, co-authored with Hans Eysenck.