The firm said it plans to locally produce the Hilux model at the new plant from February 2021 and would invest $52.6 million in the factory in a special economic zone outside Yangon.
The plant's output will be relatively modest, with plans to build 2,500 Hilux vehicles a year.
But the announcement follows the lead of other carmakers who have established local factories, including Suzuki, Nissan and Ford.
The government introduced auto import restrictions in 2017, and a fall in prices has seen the auto market grow, with many new vehicles built locally.
The Automotive Association of Myanmar said the Toyota announced was a "surprise," but welcome news.
The brand is already popular in the country, though most of its cars on the road are second-hand models.
Toyota says demand for new cases is on the rise though, nearly doubling last year to 18,000 units.