Wat Mahathat was started in 1374 A. D. during the reign of King Borommarachathirat I and finished during the reign of King Ramesuan (1388-1395). The main prang collapsed during the reign of King Songtham (1610-1628). The restoration of this prang was probably completed during the reign of King Prasatthong (1630-1655) and the height of the prang was increased at the same time.
The wat was restored again during the reign of Kin Borommakot (1732-1758) and four porticos were added to the main prang. The Wat was burned during the sacking of Ayutthaya in 1767