A spokeswoman with Alberta Occupational Health and Safety says the 33-year-old man died in hospital this morning.
The two other workers remain in hospital with critical injuries.
The trio were working on a single-family home in Fort Saskatchewan on Thursday when a gas or propane leak in the basement ignited.
Other workers on the site pulled the injured men from the home before emergency crews arrived.
The men worked for Wil-Flo Plumbing and Heating.
Relatives have identified them as 48-year-old Wes Michalycia, his brother Wilfred, who is 42, and their younger cousin Jason Michalycia of Regina.