Health anxiety has been linked with fear and anxiety regarding COVID‐19. Higher levels of health anxiety likely increased social distancing and self‐isolating during the pandemic. We investigated relations among health anxiety, fear of missing out (FOMO) on rewarding social experiences from social distancing, and consequential levels of problematic smartphone use (PSU) and gaming disorder (GD). We surveyed a broad sample of 812 U.S. and Canadian participants during the pandemic, in late‐May 2020, using the Short Health Anxiety Inventory, FOMO Scale, Smartphone Addiction Scale‐Short Version, and GD test. Significant bivariate relationships were found among health anxiety, FOMO, PSU, and GD severity. Using structural equation modeling, FOMO mediated relations between health anxiety and both PSU and GD severity. We discuss FOMO as an important variable explaining problematic digital technology use to compensate for unmet social needs from social distancing. We discuss these findings within the context of the Interaction of Person‐Affect‐Cognition‐Execution theoretical model of problematic internet use. Results offer novel insight into the role of health anxiety on FOMO from unmet social needs during the COVID‐19 pandemic, and consequential problematic internet use.