The government on Saturday reported 14 new coronavirus cases, all in quarantine, bringing the total to 3,216 cases since January.
The country has been free of local transmission for 47 consecutive days, said the Centre for Covid-19 Situation Administration.
Among the 14 new cases was a nine-year-old who travelled with her family.
A returnee, 42, arrived home from Bahrain on June 28 and was in a state quarantine facility in Chon Buri. She was asymtomatic and tested positive on July 9.
Another patient, 31, worked on a cruise ship in the United States. After returning home on Sunday, she was put in a state quarantine facility in Bangkok. She showed no symptoms but tested positive on Thursday.
The 12 others — 11 students, aged 19 to 31, and the nine-year-old girl — arrived to Thailand from Sudan on Friday and tested positive the next day, said the centre.
The new cases brought the total to 3,216, of whom 3,088 recovered, including one discharged on Saturday. Seventy patients remained in hospitals, while the death toll remained at 58.
Global Covid-19 cases in 211 countries totalled 12.62 million, up by 237,329 in the previous 24 hours, with 562,769 deaths, up by 5,364. About 58.3% of the total cases already recovered.
The US had the most cases, at 3.29 million, and the most fatalities, at 136,671. Thailand ranked 100th worldwide in the number of cases.