What is the ruling on the action of a person who receives payment for transporting employees in a car belonging to his company without its knowledge, and is the money of the questioner unlawful, given his participation in this service after becoming aware of the matter?

If the owner of the car is transgressing by transporting others in it, then it is not permissible for you to cooperate with him in this sin, based on the words of Allah Almighty: "And do not cooperate in sin and aggression." You must refrain from going with him and cancel the contract, unless you know that he has permission for that. He must also seek absolution from the entity that owns the car. As for your salary from your work, it is lawful if it is for a permissible job and you perform it as required.