University students in the UK have encountered many challenges as a result of the COVID-19 pandemic. This research aimed to track the mental well-being of a large sample of British university students (n = 554) over a one-year period of the COVID-19 pandemic, capturing data at four time points between May 2020 and May 2021. Overall retention after 12 months was 34.73%. Findings showed the COVID-19 pandemic has caused a significant, negative impact on the well-being of British university students. Students are suffering from prolonged and high levels of psychological distress and anxiety. Levels of flourishing in students are still very low. The different phases of the pandemic appear to have played an influential role in student mental health. The practical implications for higher education and recommendations for future research are discussed.