At 3pm exactly, people at six points across the city boarded trains and waited on the subway as normal, AFP reports.
As the doors shut before the next stop, the travellers removed their trousers and skirts to bare their legs while they kept on all the clothes on their upper body and got off at the platform.
An email to participants read: "If anyone asks you why you've removed your pants, tell them that they were 'getting uncomfortable'."
A number of those taking part reportedly wore festive underwear, such as polka dot bloomers.
Some people apparently took part in No Pants Subway Rides in Washington DC, San Francisco, Baltimore, London and elsewhere.
Last year, organisers claimed that 3,000 people participated in the event in New York, while others from 16 countries worldwide also joined in.