The human immunodeficiency virus (HIV) poses a severe burden on public health efforts globally. Various studies, including Population-based HIV Impact Assessment (PHIA) surveys, have revealed a high likelihood of being on antiretroviral therapy (ART) among people who are aware that they live with HIV. However, about 16.2% of PLHIV remained unaware of their HIV-positive status in 2019, and factors linked to unawareness are not well understood. This study aims to determine socio demographic, behavioral, and contextual factors associated with unawareness of HIV-positive status among people PLHIV who participated in the 2018/2019 Rwanda PHIA. It was a cross-sectional retrospective study using Rwanda PHIA data collected from October 2018 to March 2019. Using unweighted PHIA data, of the 933 PLHIV, 144 (15.4%) were unaware of the HIV status. Multivariable logistic regression was used to determine factors associated unawareness. First and foremost, socio-demographic predictors of being unaware of HIV status among PLHIV include being aged below 35 years particularly among those aged 16 to 24 years were 5.0 (aOR: 5.0 with 95% CI:2.3-10.9) than those aged 55 years old, being paid for work done in the last 12 months 1.8 (aOR: 1.8 with 95% CI: 1.2-2.8). Participants’ sex did not show any significant association with HIV status unawareness. Additionally, behavioral factors associated with unaware of HIV status among PLHIV include having had a recent HIV test in the last 3-5 years preceding data collection period (aOR: 2.1 with 95% CI: 1.2-3.6). Of all contextual variables included in the analysis like living in rural/urban and distance to a nearest health facility, and others; only context where a household had no health insurance, PLHIV were 1.8 (aOR: 1.8 with 95% CI: 1.1-2.8) times more likely to be unaware of the HIV positive status. In conclusion, unawareness of HIV status among PLHIV remains a public health threat. Thus, effort aiming to achieve the first 95% in the 95-95-95 UNAIDS target by 20230 in Rwanda should focus on young people aged 35 years and below, and increasing community awareness on available HIV testing services especially among people at high risk of infection and in rural areas of the country.