Display omitted ► Lippia sidoides essential oil was successfully encapsulated in a cashew gum/chitosan polymeric matrix. ► Nanoparticle sizes ranged from 335nm to 558nm, mainly with unimodal distribution and positive potential zeta values. ► Oil presence in nanoparticles was corroborated by FTIR and bioassays. ► Nanoparticles were effective in killing larvae of dengue vector, in a sustained release fashion. Nanogels based on chitosan and cashew gum were prepared and loaded with Lippia sidoides oil. Several parameters such as cashew gum concentration and relative oil content in the matrix had their influence on nanogel properties investigated. Nanogels were characterized regarding their morphologies, particle size distributions, zeta potential, Fourier transform infrared spectroscopy and essential oil contents. The release profile was investigated by UV/vis spectroscopy and its efficacy was determined through bioassays. Results showed that samples designed using relative ratios matrix:oil 10:2, gum:chitosan 1:1 and 5% gum concentration showed high loading (11.8%) and encapsulation efficiency (70%). Nanogels were found to exhibit average sizes in the range 335–558nm. In vitro release profiles showed that nanoparticles presented slower and sustained release. Bioassays showed that larval mortality was related mainly to oil loading, with samples presenting more effective larvicide efficacies than the pure L. sidoides oil.