Background The unavailability of data on the long-term efficacy of COVID-19 vaccines and of effective specific treatment, in addition to the emergence of new COVID-19 variants, makes nonpharmaceutical measures a mainstay for preventing the spread of infection. The policy responses of governments to the pandemic should be integrated with public behavioral changes. This study examines public attitudes, practices and perceived quarantine competency in Saudi Arabia during the COVID-19 pandemic. Methods A cross-sectional descriptive design using an online survey was employed. Convenience and snowball sampling were adopted, and 1022 valid responses were received. Findings Most respondents demonstrated satisfactory practices, including wearing face masks (76.5%), keeping a safe distance (97.8%) and appropriate hand hygiene (99.2%). Fear of stigma (8.9%) and of financial consequences (0%) were minimal drivers of underreporting of symptoms among the respondents, whereas uncertainty of the relevance of symptoms (30.3%) was a main cause of not reporting to health authorities. Most participants (73.4%) abided by government instructions due to fear of infection rather than of legal penalties. Participants, especially females and Saudi citizens, reported a high level of perceived quarantine competence (12.9 +/- 2.59). Spearman's rho correlation showed a significant positive association between wearing face masks and other precautionary practices, including keeping a safe distance (0.25, P < .01) and frequent handwashing (0.224, P < .01), which rules out the concern that wearing face masks would result in less adherence of the participants to other protective measures. Conclusion Our findings suggest that COVID-19 awareness programs should focus more on males and non-Saudi populations. We also recommend the development of screening protocols and education programs for asthmatic patients in Saudi Arabia to avoid the consequences of confusing COVID-19 symptoms with those of asthma.