The COVID-19 pandemic and subsequent lockdowns are creating health and economic crises that threaten food and nutrition security. The seafood sector provides important sources of employment and nutrition, especially in low-income countries, and is highly globalized, allowing shocks to propagate internationally. We use a resilience ‘action cycle’ framework to study the first five months of COVID-19-related disruptions, impacts, and responses to the seafood sector. Looking across high- and low-income countries, we find that some supply chains, market segments, companies, small-scale actors and civil society have shown initial signs of greater resilience than others. For example, frozen Ecuadorian shrimp and Chinese tilapia exports were diverted to alternative markets, while live-fresh supply chains were more impacted. COVID-19 has also highlighted the vulnerability of certain groups working in- or dependent on the seafood sector. We discuss early coping and adaptive responses, combined with lessons from past shocks, that could be considered when building resilience in the sector.