Purpose The purpose of this study was to assess the invariance of a culturally competent multi-lingual unmet needs survey. Methods A cross-sectional study was conducted among immigrants of Arabic-, Chinese- and Greek-speaking backgrounds, and Anglo-Australian-born controls, recruited through Cancer Registries (n = 591) and oncology clinics (n = 900). The survey included four subscales, with newly developed items addressing unmet need in culturally competent health information and patient support (CCHIPS), and items adapted from existing questionnaires addressing physical and daily living (PDL), sexuality (SEX) and survivorship (SURV) unmet need. The survey was translated into Arabic, Chinese and Greek. Rasch analysis was carried out on the four domains. Results Whilst many items were mistargeted to less prevalent areas of unmet need, causing substantial floor effects in person estimates, reliability indices were acceptable. The CCHIPS domain showed differential item functioning (DIF) for cultural background and language, and the PDL domain showed DIF for treatment phase and gender. The results for SEX and SURV domains were limited by floor effects and missing responses. All domains showed adequate fit to the model after DIF was resolved and a small number of items were deleted. Conclusions The study highlights the intricacies in designing a culturally competent survey that can be applied to culturally and linguistically diverse groups across different treatment contexts. Overall, the results demonstrate that this survey is somewhat invariant with respect to these factors. Future refinements are suggested to enhance the survey s cultural competence and general validity.