The country logged 133 new Covid-19 fatalities and 18,027 new cases over the previous 24 hours, the Public Health Ministry reported on Sunday morning.
There were 17,653 cases in the general population and 374 among prison inmates.
The Centre for Covid-19 Situation Administration said Bangkok accounted for 61 of the 133 fatalities, while another 34 deaths were in the four neighbouring provinces of Samut Prakan, Nonthaburi, Samut Sakhon and Nakhon Pathom.
Two Chinese and two Myanmar nationals were among the victims, it added.
Bangkok led all provinces with 2,899 new infections, followed by 1,259 in Samut Sakhon, 1,147 in Chon Buri and 1,113 cases in Samut Prakan.
The country also found two imported cases, one Australian and one Briton, who arrived in Phuket from the United States under the sandbox scheme.
Since April 1, when the third wave of Covid-19 began, there have been 586,451 Covid-19 patients, 377,896 of whom have recovered.
Since the pandemic started early last year, there have been 615,314 Covid-19 cases, 405,322 of whom recovered.
The death toll was at 4,896 in the third wave and 4,990 from the beginning of the pandemic early last year.
The new transmissions on Saturday were the second highest after the 18,912 cases reported on Saturday.
The government on Sunday opened vaccination registrations for foreign residents, but there were widespread reports of technical problems