An increasing number of organisations are basing their operations on temporary forms of work such as projects to cope with the needs of the modern business environment, which consequently leads to a significant growth in the demand for competent individuals who can not only adequately manage projects, but also seize the opportunities that this new way of doing business brings in the creation of strategic value for organisations. To be considered competent in the field, individuals should therefore demonstrate a certain level of knowledge, skills and abilities that are assessed, developed or improved through certification systems. Although professional certification was previously driven exclusively by the aspirations of individuals for improvement in a business context, to ensure a more professional project practice, the conditions for performing this type of work are starting to be more formalised at the level of employers (requirements in job advertisements) or the state (regulation of certification bodies or legally prescribed requirements for project positions). With the aim of examining the attitude of project professionals towards the competency-based certification in the field of project management and its legal regulations, as well as its role in ensuring the sustainable project delivery, quantitative empirical research was conducted among 246 certified project, programme and portfolio managers in Croatia. The obtained results not only indicate the importance of certification in project delivery and continuous professional development of individuals,but also emphasise insufficient recognition of certification within organisations, its connection with career progress and compliance of practices at the state level.