The stickers, distributed by the Crit'Air anti-pollution agency, have six categories, ranging from electric or hydrogen-powered vehicles - the cleanest - to diesel - the dirtiest.
On peak pollution days the dirtiest vehicles will be banned from the city's streets, a system that will replace an alternating ban based on registration numbers.
Small protest but thousands of stickers sold
About 100 motorists staged a cavalcade of ageing cars in protest on Sunday under the slogan "Non à Crit'Air, non à Big-Broth'Air".
They argue that voluntary measures, such as carparks at the city's boundaries and a discount on public transport for those who use them, are sufficient to fight pollution.
About 600,000 vehicles are driven in the French capital every day.
About 200 European towns and cities have already initiated a similar measure, according to the Paris city council, with Berlin enforcing it since 2008.
Some 2.5 million stickers have been ordered at a cost of 4.18 euros each, according to Environment Minister Ségolène Royal.
Failure to have one could mean a fine of between 68 and 135 euros but police have been told to be lenient to start with, partly because the printers are having difficulty keeping up with demand.
More Dieselgate probes possible
More Dieselgate investigations are likely following the probe into Renault that hit the headlines this week, Royal told this week's edition of the Journal du Dimanche Sunday paper.
She has no reason to believe the French carmaker used software to cheat in emissions tests as Volkswagen has been found to have done, the minister said, but the vehicles in question were way over the legal limit.
Other companies also seem to be over the limit, she added, "so there could be other investigations".