Orientia tsutsugamushi (Ot) is an obligate intracellular pathogen and the causative agent of scrub typhus spread across Asia. While its intracellular biology has been well characterised in mammalian systems, little is known about how Ot persists and adapts within arthropod hosts – its natural transmission cycle. To address this, we established novel complementary arthropod model systems, combining tick cells with in vivo Drosophila infections, to investigate Ot replication, cellular interactions, and host immune responses. Using ISE6 and BME/CTVM23 cells, we show that Ot efficiently infect and replicate in tick cells, maintaining a cytoplasmic lifestyle and budding from the host membrane as revealed by electron microscopy. Immunofluorescence analysis demonstrates dynamic regulation of the surface antigen expression during infection, suggesting stage-specific bacterial adaptation. Extending these findings to the Drosophila model, we demonstrate growth of Ot in flies, which affects fly survival and triggers innate immune response, accompanied by antimicrobial peptide production. Together, these data establish an alternative approach to investigating Orientia tsutsugamushi biology through in vivo and in vitro arthropod model systems. By bridging vector and experimental insect hosts, this work provides the first integrated framework to dissect how Ot interacts with, adapts to, and persists within arthropod cells – offering new opportunities to understand its transmission and pathogenesis from the vector’s perspective.