Objectives To determine the extent of hepatitis B virus (HBV) suppression and its association with seroclearance of hepatitis ‘e’ antigen (HBeAg) and hepatitis B surface antigen (HBsAg) in HIV/HBV-coinfected patients undergoing long-term tenofovir-based antiretroviral therapy (ART). Methods We prospectively followed 165 HIV/HBV-coinfected patients undergoing tenofovir-based ART. Serum HBV-DNA viral loads and HBeAg and HBsAg status were obtained at tenofovir initiation and every 6–12 months. We calculated the proportion achieving virological response (VR, <60 IU/mL) during follow-up. We also calculated rates of HBeAg- and HBsAg-seroclearance, which were compared between those who achieved versus never achieved VR during follow-up using an Exact binomial test. Results During a median 8.1 years (IQR = 4.0–13.2) of tenofovir treatment, 152 (92.1%) patients were able to achieve VR and 13 (7.9%) never achieved VR (median HBV-DNA at the end of follow-up = 608 IU/mL, range = 67–52 400 000). The prevalence of individuals with detectable HBV-DNA (≥60 IU/mL) decreased during tenofovir treatment: 15.1% (n = 14/93) at 5 years, 3.2% (n = 2/62) at 10 years and, 3.2% (n = 1/31) at 15 years. 44/96 HBeAg-positive patients (6.15/100 person-years) had HBeAg-seroclearance and 13/165 patients overall (0.87/100 person-years) had HBsAg-seroclearance. No difference in HBeAg-seroclearance was observed between those who achieved versus never achieved VR (7.4 versus 3.7/100 person-years, P = 0.33), while HBsAg-seroclearance was only observed in those with VR (1.0 versus 0/100 person-years, P = 0.49; respectively). Individuals with VR also had a higher frequency of undetectable HIV-RNA during treatment (P < 0.001). Conclusions During long-term tenofovir-based ART for HIV/HBV coinfection, persistent HBV viraemia is apparent, but becomes less frequent over time. HBsAg-seroclearance only occurred in those with full HBV and relatively high HIV suppression.