Boat-billed Herons are a nocturnal hunting species of bird. They eat small mammals, amphibians, worms, snails, crabs, and shrimp. They tend to hunt in shallow water among vegetation, standing over the surface of the water and watching for prey to move by. When they see suitable prey, they lunge forward and grab the prey in their beak, or scoop the water's surface with their broad beaks. They have also been observed disturbing still water and then chasing whatever small animals start to flee.

They tend to live in lagoons and estuaries, staying in one place throughout the year. They usually live in large colonies, but have been observed living alone.

Breeding occurs during the rainy season. They construct platform nests out of twigs and lay 2 to 4 blue-white eggs. They can have two successful clutches per year.

They are currently listed as "Least Concern" on the IUCN Red List because their range is so large, but their population is declining due to habitat loss.