Rotavirus (RV) is a segmented dsRNA virus causing severe gastroenteritis in infants and children, leading to more than 200’000 deaths/year globally. Its segmented genome allows for genetic reassortment, where co-infection with different strains can lead to the exchange of genome segments and the emergence of new variants. The mechanisms underlying genomic segment bundling and reassortment remain unclear. During infection, membraneless organelles called viroplasms form in the cytoplasm via liquid-liquid phase separation. These biomolecular condensates are sites of viral RNA synthesis and genome assembly, and contain all 11 RV segments, as well as viral and host proteins. Most previous studies have characterised viroplasms through live imaging of proteins or fixed imaging of RNA by smFISH. To fully determine the molecular basis of viroplasm formation and reassortment, new tools for live single-molecule RNA imaging are needed. Using reverse genetics we developed a suite of tools to investigate real-time single-molecule events during RV infection. By integrating live RNA labelling with viroplasm imaging, we visualised RNA coalescence during viroplasm formation and dissolution, and monitored coinfection with different strains. We also imaged and tracked single viral mRNAs in infected cells. These tools will provide new insights into diverse aspects of RV biology, from host interaction to genomic reassortment, and can potentially be applied to other dsRNA or segmented viruses.