The COVID-19 pandemic has affected people’s physical and mental health. Quarantine and other lockdown measures have altered people’s daily lives; levels of anxiety, depression, substance use, self-harm and suicide ideation have increased. This commentary assesses how international governments, agencies and organisations are responding to the challenge of the mental health impact of COVID-19 with the aim of informing the ongoing policy and service responses needed in the immediate and longer-term. It identifies some of the key themes emerging from the literature, recognises at risk populations and highlights opportunities for innovation within mental health services, focusing on the published academic literature, international health ministry websites and other relevant international organisations beyond the UK and Ireland. COVID-19 has challenged, and may have permanently changed, mental health services. It has highlighted and exacerbated pre-existing pressures and inequities. Many decision-makers consider this an opportunity to transform mental health care and tackling the social determinants of mental health and engaging in prevention will be a necessary part of such transformation. Better data collection, modelling and sharing will enhance policy and service development. The crisis provides opportunities to build on positive innovations: the adaptability and flexibility of community-based care; drawing on lived experience in the design, development and monitoring of services; interagency collaboration; accelerating digital healthcare; and connecting physical and mental health.