Antiretroviral therapy continues to make an enormous contribution to improving the well-being of people living with HIV/AIDS globally. In Gabon, dolutegravir is administered to PLHIV from first-line treatment. This study aimed to determine the prevalence of active HIV infection and current effectiveness rate of dolutegravir-based treatment among PLHIV in the Gabon. This study was conducted at National Public Health Laboratory from January to December 2023 among 361 PLHIV under treatment based-dolutegravir or treatment-naive. RNA extraction was carried out on the GXT extractor. HIV viral load and CD4+ count were determined using QuantStudioTM5 and BD FACS PrestoTM, respectively. A total of 361 PLHIV were included in the study. The overall prevalence of active infection among PLHIV was 21.1%. The effectiveness rate of DTG-based treatment was 85.01%. Among the 76 PLHIV with an active infection, 64.5% were on DTG-based treatment. Among PLHIV with a CD4+ count greater than 200 cel/mm3, 97.8% were PLHIV receiving DTG-based treatment. PLHIV with a CD4+ count below 200cel/mm3, singles and treatment-naive PLHIV were likely to develop an active infection (P=0.0001). The prevalence of active infection is worrying among people living with HIV/AIDS, but treatment with dolutegravir still remains effective among PLHIV in the Gabonese context.