Older workers make up a growing proportion of the workforce, and research on how best to manage them is being conducted accordingly. Here, we explored the employee retention payoff of high‐performance work systems (HPWS) and flexible work programmes (FWPs) when used with an older workforce. Drawing from the job demands‐resources model, we hypothesised that HPWS retention outcomes decrease as the workforce ages, whereas the retention capacity of FWPs increases. We also explored how the parallel provision of HPWS and FWPs affects workforce retention in more ageing workplaces. The results suggest that workforce age composition affects the HPWS‐retention relationship. However, the value of FWPs as retention tools does not vary significantly with workforce ageing. Furthermore, the provision of FWPs alongside HPWS appears to be a less‐than‐optimal approach to this retention. These findings may contribute to a better understanding of the HRM‐performance relationship, while inspiring further research into successful age‐differentiated HR strategies.