All 23 flood fatalities were caused by drowning, the Department of Disaster Prevention and Mitigation said on Wednesday.
Thailand is currently in a monsoon season, with heavy rainfalls forecast for the rest of the week.
However it was not seasonal rain alone that caused widespread floods, according to the country’s meteorological department.
The situation became exacerbated after Thailand was hit by Tropical Storm Sonca, which originated in the upper South China Sea in late July.
A total of 44 out of Thailand’s 67 provinces have been flooded.
Floodwaters in 10 provinces, mainly in the country’s northeast, are still up to two metres in depth in some places.
The hardest hit area is the northeastern province of Sakhon Nakhon, 650 kilometres from Bangkok. Its domestic airport was closed for three days before re-opening late on Monday.
Among the flooded provinces is the historic central city of Ayutthaya, popular among tourists for its many ancient Buddhist temples.