The whole dramatic incident was captured by surveillance cameras on the bus near the town of Kiezmark, west of Gdansk.
The driver suddenly slumped to the left and then fell on the floor to the right of his seat when the bus subsequently veered across the road.
A female passenger was then heard to scream in Polish, "can anyone drive" as she grabbed the wheel and attempted to steer the bus safely to a halt.
Another woman helped her as the bus swerved from one side of the road to another, hitting a road sign, the barrier and a car travelling in the opposite direction.
A man also came forward to help and, after driving for about 500m, the driver regained consciousness and managed to apply the brake.
Piotr Topolewicz, with PKS Gdansk, the bus owners, praised the women, saying they had prevented a major crash and probably saved the lives of the 20 people on board.
Local police spokesperson Marzena Szed-Sobanska confirmed that the bus had collided with a car during the incident, but no one was hurt.
One of the female passengers who grabbed the wheel praised the "instincts and reactions" of the other woman who stood up to help, saying it was because of her that she was "able to stand here today and talk about it."
The other woman did not want her name to be revealed.
The bus driver was not injured, but was taken to the hospital for tests.
Mr Topolewicz said the women would now be offered free bus service.
prevented a real tragedy