AbstractThe growing projectification trend has brought to the forefront the importance of project‐based organising as a work mode and of project‐based organisations (PBOs) as key employers. However, research in certain human resource management (HRM) areas (including voice) has been limited in PBOs because of the decentralised and changing nature of HRM functions in these types of organisations. In dynamic project organisations, voice is highly important in recruitment, innovation and improvement; it therefore has to be conceptualised systematically. To this end, we focus on project workers as the key employee group and conceptualise the determining system factors that shape their voice in PBOs. The conceptual framework is based on a systematic review of peer‐reviewed articles and contributes to employee voice theory as a vehicle for the study of voice in temporary employment relationships.