The new £1.6m scheme was launched on January 31, and will apply only to buses at this stage.
The clean air zone is aimed at reducing exhaust emissions from the city’s buses – as part of a bid to tackle pollution.
Green councillor Andy D’Agorne, who has campaigned for environmentally-friendly initiatives to reduce air pollution in York, said the move is a “major step forward in our drive to improve air quality in the city”.
He added it will benefit the health and wellbeing of residents and visitors.
Coun Paula Widdowson, executive member for climate change, said: “I am delighted that York’s new clean air zone is finally operational.
“The Liberal Democrats have been working hard to deliver a clean air zone here in York and I am looking forward to building on the work already undertaken to tackle air pollution in the city, such as introducing more electric buses on the Park&Ride network.
“We will continue to make the case that there should be central government funding made available for new initiatives to tackle poor air pollution.”
The council has awarded more than £1.6 million in funding to five bus companies to help them to make their vehicles more environmentally-friendly.
Under the plans, bus companies need to prove they have placed an order for environmentally buses.
A total of 93 buses will either be ‘retrofitted’ or replaced and every bus operating services on or within York’s inner ring road will be required to meet the Euro VI emission standards.
The only vehicles that will be exempt are those that would only enter the zone less than five times a day.
First York received the biggest grant – £1,188,000 to retrofit 66 buses.
Arriva Yorkshire, Harrogate Coach Travel, Reliance Motor Services and Transdev have also been awarded cash.
Coun D’Agorne said: “By February 2021, all but a very small number of infrequent bus services will meet the Euro VI emission standard.
“This represents a major step forwards in our drive to improve air quality in the city centre by tackling the causes of pollution, and will benefit the health and wellbeing of everyone who lives and works in York, as well as visitors to the city.”
He said air quality across York will improve.