In an increasingly volatile world, organisations must be prepared to navigate high-impact crises such as pandemics, geopolitical tensions, and disasters. As a result, resilience has become a strategic priority. Operationalising resilience, however, remains challenging due to three key barriers. First, the complex, interconnected nature of organisations makes it difficult to understand interdependencies and implement effective resilience interventions. Second, many crises are considered unimaginable, so-called Black Swans, hampering proactive resilience-building. Third, resilience is highly contextual and conceptually ambiguous, leading to uncertainty about its practical application. To address these barriers, this study investigates what decision-makers within complex systems can learn from wargaming (i.e. the practice of simulating decision-making in environments of conflict or competition) Black Swans to support the operationalisation of resilience. Based on four wargames with 57 decision-makers from aviation, defence and other sectors, we conducted a thematic analysis to interpret their outcomes. Our findings suggest that wargaming helps decision-makers (1) develop a shared understanding of their organisation within its complex system; (2) imagine the impact of type-B (unknown knowns) and type-C (ignored knowns) Black Swans on their organisation; and (3) operationalise resilience-as-an-outcome while deepening their theoretical understanding of it. Finally, conducting wargames may enhance resilience capabilities, namely shared situational awareness, the management of keystone fragilities, anticipating future developments, and sensemaking. Our findings suggest that wargaming can be a valuable tool for organisations to operationalise resilience.