EC secretary-general Puchong Nutrawong said voting had been carried out from Jan 13-21 in countries including Australia, Belgium, Israel, Libya, China, India, Taiwan, Brunei, Cambodia and Vietnam.
Voting is not yet finished in some larger countries so the final number of total overseas voters will not be known until next week.
Thailand has a total of 92 embassies and consulate offices in 67 countries. A total of 143,807 people registered for advance voting in the election.
The overseas election process will be carried out until Jan 26, which is also the date set for advanced voting to begin in Thailand.