The affected section is between Sala Daeng and Narathiwat Ratchanakarin intersections, according to BMA adviser Wichai Sangprapai.
In an attempt to tidy up the city pavement, night-time vendors have to use same-size stalls, one for each seller.
The city hall found that of about 900 vendors on Silom pavement, some 400 sell stuff during the day.
The BMA plans to open registration for the vendors in which daytime merchants can register to sell during the night as well.
The Metropolitan Police Bureau has to set the time for night stalls to ensure they will not cause traffic problems.
The city hall plans other places for vendors at other markets such as Chatuchak 2, Talat Phlu, Sanam Luang 2 and Tevarat.
A tidy Silom is needed as it is a business district affecting the country’s image.