In the era of highly active antiretrovirals, people living with HIV (PLWH) have resumed sexual activity in the context of longer and healthier lives, and thus the chances of transmitting the HIV virus, as well as the potential to be re-infected also increase. HIV treatment optimism has been found to be associated with sexual risk behaviors among PLWH in different settings. A cross sectional survey was conducted to examine the relationship between treatment optimism, safer sex burnout and consistent condom use as well as variables associated with treatment optimism in a sample of PLWH on antiretrovirals (ARVs) in Rio de Janeiro, Brazil (n = 604). Seventy-two percent of participants always used a condom in the last 6 months. Homosexual, bisexual, transexual persons were less likely to use condoms consistently than heterosexuals (AOR .58 CI .42–.78). Those who were treatment optimistic (AOR .46 CI .25–.88) were more likely not use a condom consistently in the past 6 months, as were participants who reported safer sex burnout (AOR .58 CI .36–.90). Sexual orientation, safer sex burnout, and lower education levels were significantly associated with higher treatment optimism in multivariate analysis. Study findings highlight the need to address psychosocial factors such as treatment optimism and safer sex burnout associated with lower consistent condom use among PLWH in Rio de Janeiro, Brazil.