The Big Five Inventory-2 (BFI-2) is a widely recognized tool for assessing personality traits across five domains and fifteen facets. However, its psychometric properties in non-Western cultures like Bangladesh remain unexplored. This study aimed to validate the Bangla BFI-2 (BFI-2-B) within a Bangladeshi community sample to provide a culturally adapted personality assessment tool. A cross-sectional survey was conducted on 1,095 participants, where 646 participants (59%; 358 female; Agemean = 24.25 years, SD = 4.47) passed all attention checks. Participants responded to a demographic questionnaire, Bangla Big Five-2 (BFI-2-B), and Bangla NEO Five-Factor Inventory (NEO FFI). The domain-level structural validity was analyzed using Exploratory Structural Equation Modeling (ESEM). A series of five different latent models were tested by Confirmatory Factor Analysis (CFA) for facet-level structural validity. Full Measurement invariance across gender, education level, and language were tested. The item quality was assessed using Item Response Theory analysis (IRT). Convergent and discriminant validity were assessed by correlating the BFI-2-B domains with the NEO-FFI. The BFI-2-B demonstrated high internal consistency across domains (> 0.70) and facets (> 0.60; except energy level, intellectual curiosity, and respectfulness). ESEM confirmed structural validity at the domain level (CFI & TLI = 0.96). CFA analysis revealed that at the facet level, a three-facet structure with an acquiescence factor yielded the most acceptable fit (CFI& TLI ≥ 0.95; RMSEA ≤ 0.06; SRMR ≤ 0.08). Full measurement invariance was established across gender and educational levels, but only weak invariance was found across languages, indicating linguistic challenges. The similar domains of BFI-2-B and NEO-FFI had strong correlations (r ≥ 0.59), and distinct domains exhibited low correlations, indicating strong convergent and discriminant validity. IRT analysis showed that most items had high to moderate discrimination. The BFI-2-B is a reliable and valid tool for assessing personality in the Bangladeshi context, with robust psychometric properties across domains and most facets. Addressing linguistic nuances and testing in more diverse samples can further enhance its cross-cultural applicability.The stage 1 protocol for this Registered Report was accepted in principle on 24/09/24. The protocol, as accepted by the journal, can be found at: 10.17605/OSF.IO/7DTQG.