In light of an increased push for disclosure of HIV-positive serostatus to sexual partners (partner disclosure, PD) in China as reflected by national and local policies, the objective of this study was to determine the proportion and evaluate associated factors of PD among people living with HIV/AIDS (PLWHA) in HIV/AIDS high-risk areas in southern China. Of the 946 HIV-positive individuals, the proportion of those who disclosed positive serostatus results to their sexual partners was 90.2% (625/693). Variables independently associated with non-disclosure included testing in Guangxi province (adjusted relative ratio [ARR] = 0.33), becoming infected with HIV via injecting drug use (IDU) transmission (ARR = 0.32), having not reported discussing disclosure with health department staff during post-test counselling (ARR = 0.41) and having a sexual relationship of ≤2 years' duration (ARR = 0.31). This study also identified a relatively larger differential between the proportion of disclosure to regular partners and the proportion of disclosure to casual partners (94.8% versus 13.0%) in comparison with other studies. Findings from this study may aid policies for future consideration.