Assisted HIV partner notification services provide a safe and effective way for people living with HIV (PLHIV) to inform their partners about the possibility of exposure and to offer them testing, treatment, and support. This study examined whether or not PLHIV in prison might be willing to participate in assisted HIV partner notification services and their reasons for and against disclosing their HIV-positive status to their partners. PLHIV (n = 150) recruited from Jakarta's two largest all-male prisons completed an interviewer-administered questionnaire collecting demographic and risk behavior data, and attitudes toward HIV disclosure and partner services. Among those who were sexually active and/or injecting drugs before incarceration, two-thirds (66.4%, 91/137) endorsed provider referral as an acceptable way to notify their sex partners, and nearly three quarters (72.4%, 89/123) endorsed provider referral to notify their drug-injecting partners. Only a quarter (25.1%) of participants reported that their main sex partner had ever received an HIV test. Participants with anticipated stigma were less likely to endorse provider referral for sex partners (adjusted odds ratio [aOR] = 0.58, 95% CI: 0.35, 0.96) and drug-injecting partners (aOR = 0.54, 95% CI: 0.29, 1.00). Relationship closeness was associated with higher odds of endorsing provider referral for drug-injecting partners (aOR = 2.08, 95% CI: 1.25, 3.45). Protecting partners from infection and a moral duty to inform were main reasons to disclose, while stigma and privacy concerns were main reasons not to disclose. Most incarcerated PLHIV have at-risk partners in the community who they would be willing to notify if provided with assistance. Assisted partner notification for prison populations offers a promising public health approach to accelerate diagnosis, treatment, and prevention of HIV infection in the community, particularly among women.