Cody Osterland had been serving a three-year, five-month and 15-day sentence since Oct. 10, 2014 for a number of weapon and drug-related charges.
CSC said his family has been notified.
Police and the coroner have also been notified. The circumstances of the incident are under review, as in any case of an inmate death.
Drumheller Institution is a medium security prison in southern Alberta.
A Global News request to CSC was not immediately answered.