Thailand voted to accept a military-backed constitution, results based on 80 percent of votes counted showed.
Results on Sunday from the country's Election Commission show 62 percent of the country voted for the charter while 37.9 percent rejected it.
The vote paves the way for a general election in 2017 but requires future governments to rule on the military's terms.
Al Jazeera's Wayne Hay, reporting from Bangkok, said: "We must look at how many people came out to vote because there were severe restrictions on the public leading up to this vote.
"Sixty one percent of people voted in the favour of the draft constitution and 38 percent voted for 'no'. The only result that the military was worried about before this referendum was a comprehensive 'no' vote with a very large voter turnout."
Critics, including the country's major political parties, have said the constitution is undemocratic.