One effective preventative measure to reduce the number of new HIV infections is through the uptake of daily oral HIV pre-exposure prophylaxis (PrEP). Although previous clinical trials have proven the effectiveness of on-demand PrEP uptake, daily PrEP uptake is the most popular prevention method among PrEP users and is still recommended by most healthcare professionals and organizations. Informed by the integrative model of behavioral prediction, the current study examined the socio-behavioral factors associated with PrEP non-adherence. The present study conducted a cross-sectional survey of 210 gay male daily PrEP users living in California and New York. The results showed more than two-thirds of the sample indicated that they had skipped taking PrEP within the last 30 days, averaging around four to five missed doses. General attitudes toward desirable and undesirable outcomes, perceived behavioral control, and social-level barriers were associated with daily PrEP uptake non-adherence. The findings highlight providers' role in PrEP adherence and the importance of habit-forming, which can be enhanced by cost-effective strategies and technological innovations.