The Amazon Basin harbors a high diversity of phlebotomine sand flies, including several species that act as vectors of zoonotic pathogens such as Leishmania. Land-use changes, particularly forest conversion to agriculture, alter the sand fly diversity and community structure, with implications for the transmission of American Tegumentary Leishmaniasis (ATL). We evaluated the effects of forest-to-agriculture conversion on sand fly diversity and species composition in two rural areas, on opposite sides of the Amazonas River, in the Brazilian Amazon Region. Sand flies were collected using Center of Disease Control (CDC) light traps, installed in the forest and cropland environments, at the Presidente Figueiredo (North) and Urucurituba (South) municipalities, in Amazonas, Brazil. We collected a total of 1778 phlebotomine sand flies from 15 genera and 69 species. The most abundant species were Micropygomya rorotaensis (n = 436; 24.52%), Nyssomyia antunesi (n = 297; 16.70%), Sciopemyia sordellii (n = 101; 5.68%), Bichromomyia flaviscutellata (n = 84; 4.72%) and Evandromyia monstruosa (n = 72; 4.04%). In addition, four sand fly species were recorded for the first time in the Amazonas state: Brumptomyia mesai, Pressatia calcarata, Evandromyia aldafalcaoae and Lutzomyia carvalhoi. Sand fly richness, diversity, and community composition varied between riversides and environments, reflecting strong effects of anthropogenic disturbance. Although croplands supported reduced and more heterogeneous assemblages, several medically important vector species persisted across both environments. Species turnover was high, but patterns of species loss were weak, suggesting that community reorganization was driven by non-directional compositional change process. Our results indicate that land-use change reshapes sand fly communities without eliminating disease vectors, potentially increasing ATL transmission risk at the forest–anthropic interface.