This study investigates and compares the characteristics and potential sources of carbonaceous aerosols in fine particulate matter (PM_2.5) between urban and suburban areas of Hanoi. Daily samples were collected at two sites in Hanoi, Vietnam, including HUCE (urban) and Thuong Tin (suburban), during June, July, and August 2024, corresponding to the summer period in Hanoi. The average concentrations of organic carbon (OC) were 10.80 µg/m³ at HUCE and 16.16 µg/m³ at Thuong Tin, while elemental carbon (EC) averaged 1.65 µg/m³ and 1.75 µg/m³, respectively. Carbonaceous aerosols accounted for over 30% of PM_2.5 mass at both sites, emphasizing the importance of carbonaceous matter in Hanoi’s atmospheric particulate composition. The average OC/EC ratios exceeded 2.0, suggesting a significant contribution from secondary organic carbon (SOC). SOC accounted for 59.69% of the total OC at HUCE and 48.29% at Thuong Tin, highlighting its significant presence. Source apportionment using the UNMIX model revealed three carbonaceous emission sources in Hanoi: traffic emissions, coal combustion, and biomass burning. The obtained results showed that traffic emissions were the primary contributor at HUCE (62%), whereas biomass burning was most influential at Thuong Tin (45%). Traffic emissions contributed 35% of PM_2.5 at Thuong Tin. Coal combustion contributed 35% at HUCE and 20% at Thuong Tin, underscoring its significant and consistent role in PM_2.5 pollution across urban and suburban Hanoi. These findings provide a scientific basis for targeted air quality management strategies focused on controlling combustion-related emissions.