The renewed investment in sex work programmes is not only a moral imperative but a strategic necessity for global public health. Given their significant role in the HIV epidemic, including male clients of sex workers in intervention programmes is crucial to address the broader dynamics of HIV transmission. Costing studies are essential to understanding the costs and benefits of investing in key populations such as FSWs, demonstrating that funding such programs is not only cost-effective but vital for the improvement of health outcomes among both key and general populations. By highlighting the health returns of investing in comprehensive and inclusive programs, we enable a stronger case to be made for continued and expanded support for specialized sex worker programmes.