Their range spans across several countries, including:
* Brazil: The majority of night monkey species reside in Brazil, particularly in the Amazon basin.
* Colombia: Several species can be found in the western Amazon region of Colombia.
* Peru: Night monkeys are present in the Amazonian regions of Peru.
* Ecuador: A few species are found in the eastern Amazon region of Ecuador.
* Bolivia: Night monkeys inhabit the Amazonian regions of Bolivia.
* Guyana: One species, the Guyanan Night Monkey (Aotus lemurinus), is found in Guyana.
They prefer tropical rainforests with dense foliage, where they spend most of their time in the trees.