The original temple built on Wat Phanom Yong site was probably built during the reign of King Narai in the 17th century. Legend says that the area was once a garden belonging to a royal nanny (Phra Nom) of the King named Yong and that after her death a temple was built and named in her honor. Over time, people did not pronounce the ''r'' which explains the current name of the temple. Wat Phanom Yong was deserted after the fall of Ayutthaya in 1767 and was rebuilt during the reign of King Chulalongkorn (1868-1910) and the former residence of Phra Nom Yong is now a memorial located on the opposite bank of the canal.
The temple houses a long reclining Buddha covered in gold and its ordination hall has very beautiful colorful murals.