Objectives: (1) determine if there is a correlation between disability, depression, and wellbeing in people with IBM, (2) determine if disability and depression can predict wellbeing in people with IBM, and (3) identify the prevalence of depression and impaired wellbeing in participants with IBM. Methods: In this cross-sectional study, 101 participants with IBM completed the Neuromuscular Symptom Score (NSS), Personal Wellbeing Index (PWI), and Patient Health Questionnaire-9 (PHQ-9) surveys to serve as surrogate measures of physical disability, wellbeing, and depression respectively. Results: Linear regression identified that PHQ-9 significantly predicts PWI, however NSS does not, with a negative predictive value of depression for wellbeing (-2.7513, p < 0.001) and a positive predictive value of disability for wellbeing (0.0575, p = 0.764). Moderate to severe depression was reported in 78.2% of participants, and all but one participant reported reduced wellbeing. Conclusions: Depression is a more significant predictor of wellbeing than disability in participants diagnosed with IBM. There was a high prevalence of depression and reduced wellbeing in participants, highlighting the importance of assessing these factors to optimise treatment in IBM.