It is estimated that during the period 2020–2025, about 30% of the employees at the Austrian Ministry of Defence will retire. This raises the question of how to encourage employees to share informal knowledge in order to successfully embrace organisational change in increasingly digitised environments with a view to retaining them long-term. Through the development of a three-part empirical study, this research paper investigates the role played by informal knowledge sharing networks and social media in expediting digital transformation within a public sector organisation. Our findings show that the public sector stands to benefit from informal knowledge sharing, and that both a permissive organisational culture and the provision of clearly demarcated ‘knowledge sharing spaces’ are fundamental in this respect.