Ayutthaya (also spelled Ayudhya or Ayuthia) refers to

• The old capital of Thailand, see Ayutthaya (city)
• The province around the city, Ayutthaya province
• The ruins of the old palace, see Ayutthaya historical park
• Ayutthaya kingdom as the period of Thai history (1365-1768) in which Ayutthaya was capital