In enzymology, an ecdysone oxidase (EC 1.1.3.16) is an enzyme that catalyzes the chemical reaction

ecdysone + O₂ ${\displaystyle \rightleftharpoons }$ 3-dehydroecdysone + H₂O₂

Thus, the two substrates of this enzyme are ecdysone and O₂, whereas its two products are 3-dehydroecdysone and H₂O₂.

This enzyme may or may not belong to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with oxygen as acceptor. The systematic name of this enzyme class is ecdysone:oxygen 3-oxidoreductase. This enzyme might also be called beta-ecdysone oxidase.