Organisational purpose has been found to hold an abundance of benefits for employees and the organisation alike, including improved motivation, longevity, life and job satisfaction, meaning, engagement, wellbeing, organisational resilience, long-term financial performance, higher customer satisfaction, reduced turnover intention and more. However, issues with the conceptualisation of purpose arise due to the inconsistency of constructs and scales utilised in this area. Additionally, it is unclear how a sense of purpose at work and views of organisational purpose interact to influence employee outcomes. The present study firstly distinguishes between perceived organisational purpose and sense of purpose at work. Secondly, it investigates the direct effects of perceived organizational purpose and its four internal dimensions of POPContribution, POPAuthenticity, POPGuidance, and POPInspiration, and individual sense of purpose at work on mental wellbeing and engagement. Thirdly, it looks at the effect of varying congruence and discrepancy levels with perceived organisational purpose and sense of purpose at work on the outcomes variables of mental wellbeing and engagement. An online survey with 202 working professionals was conducted, with polynomial regression and response surface methodology being used to explore the analysis. The highest levels of mental wellbeing and engagement were observed when there was congruence at high levels with perceived organisational purpose and sense of purpose at work, while the lowest levels of mental wellbeing were found when congruence was at low levels. Sense of purpose at work overall was found to be a much stronger predictor of mental wellbeing and engagement relative to perceived organisational purpose. The study underscores the importance of alignment between individual and organisational purpose in the workplace to maximise outcomes for employees.