The new vaccination unit at the Port Authority Stadium joins two others launched last Tuesday at Tesco Lotus Rama IV and Wat Klong Toei School.
Bangkok Governor Aswin Kwanmuang said that about 50,000 of the 80,000 slum residents in Klong Toei must be vaccinated to contain the outbreak, which emerged in April.
Each vaccination unit is handing out about 1,000 queue cards per day.
A total of 11,211 people had been vaccinated at the mobile units as of Sunday (May 9).
The Bangkok Metropolitan Administration (BMA) aims to vaccinate around 2,500 to 3,000 people per day until May 19.
The BMA also launched a swab-test campaign in Klong Toei communities on April 27. As of Sunday, 19,983 people had been tested.
A total of 654 tests came back positive 13,629 were negative, and another 5,700 have yet to come back from the lab.