The worker was killed after being run over by a mobile crane that was removing the Sauber of Esteban Gutierrez from the side of the track after he crashed in the closing stages.
Vettel, oblivious to the unfolding tragedy, captured his first Formula One victory on North American soil to extended his overall lead in the championship to 36 points over Ferrari's Fernando Alonso, who finished second.
But hours later the FIA, the sport's governing body, announced the death of the marshal.
"The recovery vehicle had lifted the car to return it to the pits and while doing this the worker dropped his radio and attempted to pick it up," said the FIA statement.
"As he did this, he stumbled and was hit and run over by the recovery vehicle."
The marshal could not be seen by the driver of the crane and suffered serious injuries.
The FIA said the worker was transferred by helicopter to the Sacre-Coeur hospital in Montreal for treatment in its traumatology department.
However the marshal, as yet unidentified, succumbed to his injuries on Sunday night.
He was the first marshal to die at a race since the 2001 Australian Grand Prix when Graham Beveridge was struck by a tyre that flew through a gap in safety fencing after Jacques Villeneuve and Ralf Schumacher collided.
The previous year, marshal Paolo Ghislimberti died at the Italian Grand Prix after being struck by a wheel that flew over the barriers after an opening lap crash.