In enzymology, a 2,3-dihydroxyindole 2,3-dioxygenase (EC 1.13.11.23) is an enzyme that catalyzes the chemical reaction

2,3-dihydroxyindole + O₂ ${\displaystyle \rightleftharpoons }$ anthranilate + CO₂

Thus, the two substrates of this enzyme are 2,3-dihydroxyindole and O₂, whereas its two products are anthranilate and CO₂.

This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O₂ as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O₂. The systematic name of this enzyme class is 2,3-dihydroxyindole:oxygen 2,3-oxidoreductase (decyclizing). This enzyme participates in tryptophan metabolism.