Introduction:The Birmingham 2022 Commonwealth Games (CWG) met the World Health Organization (WHO) definition of a mass gathering: events attended by sufficient people to strain the planning and response resources of a community, state or nation’. It was a key opportunity for the UK in terms of tourism and economy, but a major challenge in terms of the potential for adverse events e.g. infectious disease outbreaks, terrorist attacks. This increased scrutiny and threatened reputational risk. For UKHSA, as a new organization amidst a rapidly changing public health landscape–continued COVID-19 pandemic and increases in Monekypox, this was a very public test.Method:In 2021, a small team was established to accelerate preparation including: assurance structuresadvice to the Organizing Committee and Government departmentsadvice on COVID-19 including testing policystaff/stakeholder preparation through exercising/trainingincreased staff numbers and skill mix able to adaptbudgetoperational response structureplans in place and tested for a health protection response in the event of an incidentother mass gatherings reviewed for transferable learning enhanced surveillance systemsResults:Daily epidemiology reporting provided reassurance that there were no significant public health issues requiring escalation. Enhanced surveillance provided reassurance to the community that there were no population ill effects linked to the CWG. Overall, COVID-19 positivity was low. No outbreaks were detected linked to the CWG.Conclusion:The UKHSA successfully identified, planned and prepared for and mitigated the risks of a mass gathering of 1.5 million people. Early engagement, support, advice and cross- government collaboration has been regarded as exemplary with surveillance data indicating no outbreaks linked to the Games. Despite the breadth of risks visitors were able to attend the event in contrast to the restrictions placed at the Tokyo Olympics. This contributes to the worldwide body of knowledge for planning and delivering mass gatherings – sporting or otherwise.