Wat Phra Si Mahathat Wora Maha Viharn (Thai: วัดพระศรีมหาธาตุวรมหาวิหาร) is a Buddhist temple in the Bang Khen District of Bangkok.

The temple would be built close the Constitution Defense Monument in Bang Khen District's Lak Si Circle, which was near the site of a battle between the government led by the Khana Ratsadon (People's Party) and royalists under Prince Boworadet in 1933.

The temple is significant: "not only for the government to ideologically proclaim their victory over the conservative royalists, but also to symbolize the efforts by the People’s Party to shape the political landscape of the country.

As result of this trip the minister received a piece of the Buddha's relic found at Dharmarajika Stupa, Taxila, modern day Pakistan.

In 1941 the government raised the status of the temple to that of a first-class royal monastery and the name was altered to Wat Phra Si Mahathat Wora Maha Viharn.