Changes in daily life related to COVID-19 have impacted e-cigarette use, particularly in young adults. This cross-sectional mixed-methods study explored young adults' perceptions regarding how COVID-19 influenced their e-cigarette use. We analyzed Fall 2020 survey data from 726 past 6-month e-cigarette users (mean age=24.15 years, 51.1% female, 35.5% sexual minority, 4.4% Black, 10.2% Asian, 12.1% Hispanic) and Spring 2021 semi-structured interview data among a subset of 40 participants (mean age=26.30 years, 35.0% female, 45.0% sexual minority, 5.0% Black, 22.5% Asian, 12.5% Hispanic). Participants were drawn from 6 metropolitan statistical areas with varied tobacco and cannabis legislative contexts. Among survey participants, 44.4% also smoked cigarettes, 54.0% other tobacco products, and 60.1% used cannabis. They reported various changes in their daily lives, including changes in the nature and/or status of employment (e.g. 15.3% were laid off, 72.8% experienced household income loss). Regarding changes in e-cigarette use since COVID-19, 22.6% tried to cut down and 16.0% tried to quit. Interview participants commonly indicated that they increased their use due to stress, boredom, changes in accessibility, and/or changes to daily environment that made e-cigarette use more feasible. Results highlight the importance of promoting opportunities for young adults to build relationships to decrease stress, foster a sense of belonging, and increase quality of life (e.g. increasing the accessibility to mental health and social support services, intentionally engaging young adults in pandemic-appropriate community-building and extracurricular activities). This research may help to inform future e-cigarette cessation interventions that consider the unique challenges of societal stressors, such as pandemics.