Resumo. Roselle (Hibiscus sabdariffa L.), also known as red sorrel, is an unconventional food plant (UFP) recognized for its nutritional, medicinal, and economic importance. Its primary commercial product is the calyx, which is susceptible to attack by the cotton seed bug [CSB; Oxycarenus hyalinipennis (Costa, 1847) (Hemiptera: Oxycarenidae)], a pest associated with Malvaceae crops such as cotton. However, until now, there have been no records of this pest causing damage to roselle plants in Brazil. This study aims to report the occurrence of O. hyalinipennis on roselle and to describe the injuries inflicted by this pest. Observations were conducted in June 2024 at the Campo Experimental Santa Rita of EPAMIG Centro-Oeste, in Prudente de Morais, Minas Gerais, on an organically cultivated crop. The damage initially appeared as translucent spots on the surface of developing calyces, progressing to darkened cracks, deformations, necrosis, fruit abortion, and weight loss, which rendered the calyces unmarketable. CSB individuals were observed at various developmental stages, primarily inside the calyces near the seeds. Initially, the symptoms were misdiagnosed as a fungal disease; however, the correct association with the insect was only established during post-harvest inspection. This constitutes the first record of O. hyalinipennis causing damage to roselle in Brazil, underscoring the importance of monitoring this crop to prevent losses and ensure the quality of the final product.