Chilli veinal mottle virus (ChiVMV) causes significant economic loss to chilli cultivation in northeastern India, as well as in eastern Asia. In this study, we have developed a single-tube one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for rapid, sensitive and specific diagnosis of ChiVMV. Amplification could be visualized after adding SYBR Green I (1000×) dye within 60 min under isothermal conditions at 63 °C, with a set of four primers designed based on the large nuclear inclusion protein (NIb) domain of ChiVMV (isolate KC-ML1). The RT-LAMP method was 100 times more sensitive than one-step reverse transcription polymerase chain reaction (RT-PCR), with a detection limit of 0.0001 ng of total RNA per reaction.