The neurodiversity movement has reshaped how autism is conceptualized, represented, and increasingly researched. Yet Autistic people with complex support needs (CSN) – including those who are minimally- or non-speaking, use augmentative and alternative communication, or require intensive daily support – remain disproportionately excluded from both neurodiversity discourse and participatory research. In this commentary, we clarify the relationship between the neurodiversity paradigm and Autistic people with CSN, addressing persistent misconceptions that the movement overlooks disability or minimizes support needs. Drawing on theoretical analysis, empirical evidence, and recent research experiences involving Autistic people with CSN, we argue that when applied rigorously, the neurodiversity paradigm offers a powerful framework for advancing autonomy, dignity, and inclusion for those with the most complex support needs. We examine structural, attitudinal, and methodological barriers that limit participation, and highlight emerging studies demonstrating that inclusive, co-produced research with Autistic people with CSN is both possible and beneficial. Finally, we offer four actionable recommendations to guide researchers in creating conditions that support meaningful involvement of Autistic people with CSN throughout the research process. Ensuring that participatory approaches include those historically excluded is not only an ethical imperative but essential for producing accurate, responsive, and socially just autism research.