Author summary Chikungunya virus (CHIKV) is an arbovirus, where in Africa non-human-primates (NHPs) are hosts of the sylvatic transmission cycle. Since 2014 in Brazil CHIKV is maintained in urban cycles, involving humans and Aedes aegypti mosquitoes. We have limited knowledge regarding CHIKV occurrence and implications in rural and sylvatic cycles where neotropical NHPs are present. In 2021 and 2022, we studied Culicidae mosquitoes and Leontopithecus chrysomelas (golden-headed lion tamarin -GHLT-), an endangered species endemic to the Atlantic Forest in Southern Bahia State, Brazil, at Ilhéus and Una municipalities. There was no evidence of genetic material of the virus in the GHLT and mosquitos, but we did find neutralizing antibodies as evidence of natural CHIKV exposure among free GHLT, that were present for at least five months. This could mean that GHLTs i) are susceptible to CHIKV infection, ii) may have a potential role as reservoir, and iii) are also important to include it in the epidemiological surveillance of arboviruses. Although we did not find a difference in the antibody titles in the tamarins between inhabiting the different land covers and soil uses, this endangered species could be infected in anthropogenic altered regions such as rural areas, as a consequence of anthropogenic pressure.