This study investigates the association between underemployment and job satisfaction among part-time workers across the period 2002–2014, given that both are increasingly important phenomena within the Australian labour market, and currently under-researched. We delve deeper into this nexus by extending the focus of job satisfaction beyond overall job satisfaction, including another five workplace satisfaction domains. This is done to see if the association is sensitive to specific aspects of work. We find that being underemployed is negatively associated with job satisfaction, across all workplace satisfaction domains. Further, we find that the underemployment-job satisfaction nexus to be somewhat gendered. Specifically, we report that underemployed males have a greater negative association with job satisfaction relative to their female peers. These results suggest that part-time underemployment is a significant (amounting to around 94% of the entire underemployed people in Australia) but well-hidden issue within the Australian labour market, and the consequence of this for job satisfaction are pronounced.