<p>Beet curly top Iran virus (BCTIV; <i>Becurtovirus betae</i>, family <i>Geminiviridae</i>) is widespread in crop-growing regions across Iran. In this study, BCTIV was detected in a severely infected cantaloupe (<i>Cucumis melo</i> L.) farms in Khorasan Razavi Province, northeastern Iran. The complete genome of a cantaloupe isolate of the virus shared 87.15–99.44% nucleotide identities with available sequences in GenBank, showing the highest identity (99.44%) with an isolate recovered from cowpea in the same Province. Phylogenetic analysis revealed a clear association between genetic clustering and geographic origin, with the cantaloupe isolate grouping with other northeastern Iranian isolates and one Turkish isolate. Given the widespread occurrence of the promiscuous betasatellites, tomato leaf curl betasatellite (ToLCB; <i>Betasatellite solani</i>) and okra leaf curl Oman betasatellite (OLCOMB; <i>Betasatellite abelmoschusomanense</i>) in Iran, we evaluated their potential interaction with BCTIV using agroinoculation assays. Sugar beet and cantaloupe plants were inoculated with infectious clones of BCTIV alone or in combination with ToLCB or OLCOMB. Co-inoculation did not result in enhanced symptom severity compared with BCTIV alone, and neither betasatellite was detected in inoculated plants by PCR. However, symptom onset in sugar beet inoculated with BCTIV + ToLCB occurred slightly earlier than in plants inoculated with BCTIV alone or with BCTIV + OLCOMB. These findings expand the known host range of BCTIV to include cantaloupe and indicate that, despite their broad host and helper virus associations, ToLCB and OLCOMB are not efficiently maintained by BCTIV. The results contribute to a better understanding of interactions between a becurtovirus and two betasatellites and their implications for disease development.</p>