The China GAVI Project (CGP) was initiated in 2002 to provide hepatitis B (HB) vaccine to infants born in the less developed areas of China including the Western provinces and poverty counties of Middle provinces, to prevent the consequences of hepatitis B virus infection. By 2009, the project areas had raised coverage of 3 doses of HB vaccine and timely birth doses to almost 90% among infants, comparable to those in wealthier Eastern provinces, and reduced HBV prevalence to <1% among children in these areas. We estimated the impact in disease prevented by HB vaccine in China between 1992, when the vaccine was routinely recommended, and 2009, and in CGP areas for the years 2003-2009, when the CGP was active. A published model was used to estimate the burden of chronic and acute HBV infection and death prevented due to HB vaccination in China and the CGP areas using data from national serosurveys in China in 1992 and 2006, and HB vaccine coverage from surveys in 2004, 2006 and 2010. We used sigmoid modeling to estimate vaccine coverage nationally, regionally, and CGP areas. We also estimated the incremental impact of the CGP on HB vaccine coverage in those underserved areas. Our findings suggest that between 1992 and 2009, HB vaccination in China has prevented 24 million chronic HBV infections and 4.3 million future deaths due to cirrhosis, hepatocellular carcinoma and acute hepatitis. During the CGP between 2003 and 2009, an estimated 3.8 million chronic HBV infections and 680,000 deaths were prevented in CGP areas. We found that the CGP funding increased HB vaccine coverage in project areas by 4-15% for HB3 and 4-27% for timely birth dose beyond the coverage expected without the CGP. The CGP represents a highly successful public health collaboration between the national government and international partners.