Phycourobilin is an orange tetrapyrrole involved in photosynthesis in cyanobacteria and red algae.

This chromophore is bound to the phycobiliprotein phycoerythrin, the distal component of the light-harvesting system of cyanobacteria and red algae (phycobilisome).

[1] When bound to phycoerythrin, phycourobilin shows an absorption maximum around 495 nm.

It can also be linked to the linker polypeptides of the phycobilisome, in which its precise role remains unclear.

Phycourobilin is found in marine phycobilisome containing organisms, allowing them to efficiently absorb blue-green light.