Interferon-based regimen has been used to treat hepatitis D virus (HDV) super-infection on top of hepatitis B virus (HBV) carriers; however, viral relapse is frequent after stopping therapy. Recently, quantitative hepatitis B surface antigen (qHBsAg) was introduced to help the management of chronic hepatitis B (CHB). Little is known about its role in the treatment of HBV and HDV dual infection. Herein, we reported a 45-year-old male HBV carrier with HDV co-infection who received combination therapy of pegylated-interferon α-2a plus entecavir. The qHBsAg level was adopted as the treatment guidance and a consolidation therapy of 12 months was continued after HBsAg loss. The patient achieved HBsAg seroconversion with HDV RNA undetectable after 35 months of combination therapy and sustained therapeutic response 12 months post-therapy. Therefore, personalized response-guided therapy by using qHBsAg may be an option for the treatment for HBV and HDV dual infection.