It also said that wearing of masks in Delhi was compulsory for everyone.
Announcing the decision while hearing a case involving fines for not wearing a mask while driving alone, Judge Pratibha M Singh said, "Even if you are alone in the car, why object to wearing a mask? It is for your own safety."
"When a car stops at a traffic signal, a driver often has to roll down their window. The coronavirus is so contagious that even in that time, anyone can be infected," the court said.
"This was the least anyone could do to be safe against Covid," she added.
"Scientists and international governments advise wearing of a mask. The challenge of the pandemic was enormous and the wearing of face masks is necessary whether a person is vaccinated or not," the Delhi HC said.
A single judge bench of Justice Prathiba M Singh also dismissed all petitions challenging the fines imposed on those people who did not wear masks when they were alone in their cars.
The Union Health Ministry had earlier informed the Delhi HC that there was no rule that a lone driver had to wear a mask. But every state had the right to make its own rules and enforce them, the ministry had stated.
The Aam Aadmi Party government has argued in favour of masks for all in private or public vehicles and had also passed such an order in April 2020.