 The study evaluated the effectiveness of a mobile-based app called Foundations in Reducing Anxiety and Improving Mental Well-Being in Adults with Self-Reported Symptoms during the first wave of the COVID-19 pandemic in the United Kingdom. The intervention group showed significant improvements in measures of anxiety, resilience, sleep, and mental well-being within two weeks of using Foundations, with further improvements emerging at Week 4. Perceived stress was also reduced, although the difference did not reach statistical significance relative to the control group. Overall, the study provides evidence that Foundations can be a scalable, cost-effective, and accessible solution to enhance mental well-being during times of crisis. This article was authored by Silvina Kachuarasalars, Bartwamie Skorolski, Inakia Steligari, and others.