The 2013 Lancet Commission Report, Global Health 2035, rightly pointed out that we are at a unique place in history where a "grand convergence" of health initiatives to reduce both infectious diseases, and child and maternal mortality - diseases that still plague low income countries - would yield good returns in terms of development and health outcomes. This would also be a good economic investment. Such investments would support achieving health goals of reducing under-five (U5) mortality to 16 per 1 000 live births, reducing deaths due to HIV/AIDS to 8 per 100 000 population, and reducing annual TB deaths to 4 per 100 000 population. Treatment as prevention (TasP) holds enormous potential in reducing HIV transmission, and morbidity and mortality associated with HIV/AIDS - and therefore contributing to Global Health 2035 goals. However, TasP requires large financial investments and poses significant implementation challenges. In this review, we discuss the potential effectiveness, financing and implementation of TasP. Overall, we conclude that TasP shows great promise as a cost-effective intervention to address the dual aims of reducing new HIV infections and reducing the global burden of HIV-related disease. Successful implementation will be no easy feat, though. The dramatic increases in the numbers of persons who need antiretroviral therapy (ART) under a TasP approach will pose enormous challenges at all stages of the HIV treatment cascade: HIV diagnosis, antiretroviral (ARV) initiation, ARV adherence and retention, and increased drug resistance with long-term enrollment on ART. Overcoming these implementation challenges will require targeted implementation, not focusing exclusively on TasP, most-at-risk population (MARP)-friendly services for key populations, integrating services, task shifting, more efficient program management, balancing supply and demand, integration into universal health coverage efforts, demand creation, improved ART retention and adherence strategies, the use of incentives to improve HIV treatment outcomes and reduce unit costs, continued operational research and tapping into technological innovations.