Public organisations are often described as being subject to types of complexity that result from the interorganisational structure of governance networks. Transparency programmes add another level of complexity due to increased information openness. However, neither the nature of this complexity nor the network management approaches needed for transparency programmes has been conceptually developed. To address this gap, this article brings together governance complexity theory and knowledge management theory. An empirical model is tested using the case of police open data with regression analysis and 22 expert interviews. The results show that institutional and environmental complexity such as budget pressures, legal-normative constraints, and task complexity exert a negative influence on police information openness. However, network knowledge management practices including developing mission focus on people and communication and overcoming organisational boundaries through interorganisational collaboration can counteract these problems of complexity.