Assumption College Thonburi (Thai: โรงเรียนอัสสัมชัญธนบุรี) is a private Catholic school located in Bangkok, Thailand.

It is the eighth private school founded by the St. Gabriel Foundation in Thailand.

John Mary Jesus Salas Esquiroz of the Saint Gabriel foundation in 1961.

The logo has white and red stripes and is in the shape of a shield and the acronym word "ACT" features in blue and is at the centre of the school's crest.

Assumption College Thonburi English Program has a contract with the University of Oregon whereby students of one institution study in the other for a semester.