Anthropogenic climate change, caused by greenhouse gas emissions and other disruptions, is reshaping our planet and its ecosystems. Human activity is damaging forests that currently support our closest living relatives. This is especially true in the modern context, where logging, bushmeat hunting and other direct threats are also affecting the same habitats at the same time. However, the effects of climate change on New World monkeys inhabiting South America are relatively unexplored. This research aimed to find out how future climatic changes will influence the diversity and distributions of monkeys in the Callitrichidae family (marmosets and tamarins). The study species are all heavily affected by anthropogenic activity and listed on the IUCN Red List as Critically Endangered, Endangered or Vulnerable. They include black-faced lion tamarin (Leontopithecus caissara), cotton-headed tamarin (Saguinus oedipus), pied tamarin (Saguinus bicolor), golden-lion tamarin (Leontopithecus rosalia), black-handed tamarin (Saguinus niger) and Goeldi’s monkey (Callimico goeldii). To achieve our aim, we used ArcGIS and MaxEnt to produce species distribution models (SDMs) of current and future monkey habitats under the effects of climate change scenarios from two representative concentration pathways (RCP2.6 and RCP6.0) and three general circulation models (CCSM4, HadGEM2-ES and MIROC-ESM) for 2050 and 2070. Model performance was high with AUC scores ≥0.924, with temperature and precipitation variables identified as highly important to all models. On average, all species show losses in most scenarios, some of them substantial (>25%). However, in several scenarios four of six species show a gain by 2050 and 2070. Saguinus niger is predicted to be most at risk and Leontopithecus rosalia the least. These results are used to propose future conservation strategies to mitigate negative effects and tackle the Callitrichidae’s uncertain futures.