Current consensus is that poor mental health outcomes are a likely outcome of the multiple stay-at-home mandates (i.e., ‘lockdowns’) during the COVID-19 pandemic. Such lockdowns are characterised by loneliness, which is known to adversely impact mental health. Other factors, such as video gaming, have previously been associated with positive mental health outcomes. Indeed, evidence suggests that lockdowns led to a substantial increase in the number of people engaging with gaming. Therefore, in the present paper, we investigated the relationship between video gaming, loneliness, and mental health outcomes using online survey measures during three national lockdowns. We found that depression, anxiety, and stress increased from baseline during the first lockdown only, while loneliness increased relative to baseline in all three lockdowns. Time spent gaming had no direct relationship with mental health outcomes, nor was this relationship moderated by loneliness. While lockdown alone did not impact mental health, loneliness during lockdown was consistently associated with poor mental health outcomes. Our results add to the existing body of literature and emphasise the need for targeted public mental health interventions to improve public mental health following the COVID-19 pandemic. Data and analysis code associated with this project is accessible at https://osf.io/d5byr/.