There were 4,971 new Covid-19 cases and 33 more fatalities registered during the previous 24 hours, the Public Health Ministry reported on Thursday morning.
There were 4,773 cases in the general population and 198 among prison inmates.
The number of new cases rose from 4,886 announced on Wednesday, when the country recorded 43 more deaths.
On Wednesday, 5,402 Covid-19 patients were discharged from hospitals after recovering from the coronavirus.
Since April 1, when the third wave of Covid-19 began, Thailand has treated 2,096,866 Covid-19 patients, 2,003,730 of whom have recovered to date.
Since the pandemic started early last year, there have been 2,125,729 Covid-19 cases, with 2,031,156 complete recoveries so far.
The death toll stood at 20,753 during the third wave and 20,847 since the beginning of the pandemic.
The 33 latest fatalities were aged 28 to 88 years and included two Myanmar nationals.
Bangkok recorded three new deaths and another six were reported in the adjacent provinces of Pathum Thani (2), Samut Sakhon (2), Nakhon Pathom (1) and Samut Prakan (1).
Other central plain provinces further from the capital recorded three more deaths - in Kanchanaburi, Chon Buri and Ratchaburi.
The South reported 10 deaths – in Chumphon (2), Pattani (2), Yala (2), Surat Thani (2), Trang (1) and Phangnga (1).
The North saw six more fatalities, all in Chiang Mai.
The Northeast had five fatalities - in Nakhon Ratchasima (2), Roi Et (1), Amnat Charoen (1) and Udon Thani (1).
The 4,971 new cases included 4,762 local infections and 11 imported cases. Of the local infections, 4,599 were confirmed at hospitals and 163 via mass testing.
Bangkok had 778 new cases, followed by 329 in Nakhon Si Thammarat, 302 in Songkhla, 208 in Chiang Mai, 196 in Surat Thani, 140 in Samut Prakan, 139 in Chon Buri, 138 in Pattani, 133 in Prachuap Khiri Khan and 102 each in Khon Kaen and Yala.
The 11 imported cases were from the United Kingdom (1), Russia (4), the United States (1), Germany (1), the Maldives (1) and Cambodia (3).
On Wednesday 73,726 people received Covid-19 treatment at hospitals (down from 74,190), including 1,355 seriously ill patients (up from 1,351) and 346 dependent on ventilators (up from 340).
Global Covid-19 cases rose by 662,441 in 24 hours to 263.73 million. The worldwide death toll went up by 8,212 to 5.24 million.
The US had the most cases at 49.57 million, up 120,441, and the most deaths at 805,004, up 1,633.