Singapore is also sending 200,000 rapid antigen test kits and 500,000 nasopharyngeal swabs as part of the deal.
The shipment is scheduled to land at Suvarnabhumi Airport on Saturday.
The Foreign Ministry made a similar deal with Bhutan in August under which Thailand received 150,000 doses of the AstraZeneca vaccine.
Under the cooperation, Thailand is expected to return the same number of doses once the vaccine becomes more easily available.