Brinjal is a highly cultivated vegetable in Bangladesh facing significant yield challenges due to pest infestations. This has led to innovative solutions in pest management such as the introduction of transgenic brinjal. We explored the seasonal patterns of insect pest incidences on genetically modified (Bt) and non-genetically modified (non-Bt) brinjal varieties. This study compared the incidence and infestation of the major insect pests in two different genotypes of brinjal: BARI Bt brinjal 2 and BARI brinjal 4. The experiment was conducted on a central farm of Sher-e-Bangla Agricultural University, Dhaka, in rabi season. The primary pests documented included the brinjal shoot and fruit borer (Leucinodes orbonalis), jassid (Amrasca biguttula biguttula), aphid (Aphis gossypii), whitefly (Bemisia tabaci), and epilachna beetle (Epilachna dodecastigma). Results indicated that shoot and fruit borer incidence was notably lower in Bt brinjal compared to non-Bt counterparts, demonstrating the effectiveness of the Bt gene in reducing damage. Conversely, non-target pests such as aphids, jassids, and whiteflies showed no significant differences in population levels between the two brinjal types, emphasizing that Bt modification did not extend protection against these sucking pests. The seasonal peak for the shoot and fruit borer was observed from mid-February to March, coinciding with the reproductive stage of the crop, where infestations surged, resulting in substantial damage to non-Bt brinjal. Epilachna beetle populations peaked in late February, correlating with favorable temperature and humidity. These findings reveal that while Bt brinjal effectively mitigates damage from specific borers, an integrated pest management approach is essential for comprehensive control, particularly for non-target sucking pests. This dual strategy could pave the way for more resilient and sustainable brinjal cultivation in Bangladesh.