Background Challenges to antiretroviral therapy adherence are well-known and continue to be a major hurdle in HIV care. The objective of this paper is to identify barriers to antiretroviral therapy (ART) adherence that are relevant to HIV care from the perspective of people living with HIV and healthcare and social service professionals. Methods This study used an online survey design to collect information from the two groups. A total of 100 areas that covered six domains and 20 subdomains were administered to people living with HIV and care professionals in Canada and France. The survey asked participants to rate the importance of each area for HIV care on a four-point Likert scale. Any areas rated 3 or 4 were considered important and ranked. A Chi-square test was conducted for the difference between the groups, people living with HIV and professionals, and between women and men. Results A response rate of 87% (58/66) in Canada and 65% (38/58) was achieved. 15 of 43 (35%) areas were endorsed as important barriers by both groups, across countries and sex-covering subdomains — drug cost coverage, challenging material circumstances, HIV stigma, and privacy concerns, affect, motivation, beliefs, acceptance of HIV, comorbidity, side effects, and demands and organisation of daily life. People living with HIV identified two, and care professionals identified nine, additional areas as important barriers to HIV care across different domains and subdomains. Conclusion The study identified some common and distinct barriers to ART from the perspective of the people living with HIV and care professionals.