Background: The COVID-19 pandemic intensified health anxiety, a common and costly condition marked by excessive fear of illness and functional impairment. Despite growing prevalence and impact, health anxiety remains under-recognized in clinical practice. Scalable, accessible interventions such as internet-based cognitive behavioral therapy (iCBT) are needed to address this gap.Methods: A three-arm randomized controlled trial with waitlist control group was conducted to evaluate two self-guided digital interventions for health anxiety: THIS WAY UP iCBT and 90SecondHealth Anxiety compared to a control group. Canadian adults (N=278) meeting eligibility criteria were randomized (1:1:1). Assessments occurred at baseline, post-intervention, and at one- and three-month follow-ups. Primary outcomes were health anxiety, depression, and generalized anxiety. Data were analyzed using mixed-effects regression models under both intention-to-treat and per-protocol frameworks. Non-inferiority was tested using a predefined margin.Results: Both interventions led to improvements in health anxiety relative to waitlist control, though effect magnitude and timing varied. THIS WAY UP iCBT demonstrated significant reductions at all time points, whereas 90SecondHealth Anxiety showed a delayed effect, achieving statistical significance only at the 3-month follow-up. Non-inferiority analysis indicated that the two interventions were comparable at the 3-month follow-up. Both interventions yielded modest improvements in depressive symptoms, while generalized anxiety reductions were observed only in the THIS WAY UP iCBT group. Sex-based analyses revealed stronger and more consistent effects among female participants.Conclusions: Findings support the effectiveness of digital interventions for health anxiety and highlight the potential of brief, low-intensity programs as scalable alternatives to clinical CBT. Integration of such interventions into stepped-care models may optimize resource allocation and improve access. Future research should examine mechanisms of change, personalization strategies, and long-term outcomes.