A Syncrude employee operating an excavator was killed Sunday at the Aurora mine site 70 kilometres north of Fort McMurray.
Emergency crews were called to the incident at around 5 p.m., Syncrude said in a news release Monday.
The employee was "fatally injured despite emergency response efforts," Syncrude said.
"In an organization like ours where safety is the top priority, it's tremendously difficult when we experience such a tragic loss," Andrew Rosser, Syncrude's senior vice-president, production, said in a statement.
"We are deeply saddened by this loss and our thoughts are with the employee's family and friends at this difficult time."
No other workers were injured.
A contract worker was killed at the Aurora site last year while doing drilling work.
Syncrude said Monday it is working with RCMP and Occupational Health and Safety and has launched its own investigation into the incident.