The decree, which includes a ban on miniskirts, was brought in by authorities in Spino d'Adda, a town south of Milan, Il Messaggero reported.
Those caught flouting the rule will face a fine of up to €500.
In a move aimed at increasing their safety, deputy mayor Luciano Sinigaglia said the sex workers should be treated the same as road workers, and should be obliged to wear clothes that make them more visible.
The decree, which will take effect in September, comes just months after authorities in San Genesio, a town near the northern city of Bolzano, ordered sex workers to wear reflective vests and trousers.
However, the town was slightly more careful with its choice of words, saying the decree affected all those “who walked or stopped” at night on a particular stretch of road outside the town.
It was also seen as a tactic to rid San Genesio of prostitutes all together.