Effective implementation of policies for expanding antiretroviral therapy (ART) requires a well-trained and adequately staffed workforce. Changes in national HIV workforce policies, health facility practices, and provider experiences were examined in rural Malawi and Tanzania between 2013 and 2017. In both countries, task-shifting and task-sharing policies were explicit by 2013. In facilities, the cadre mix of providers varied by site and changed over time, with a higher and growing proportion of lower cadre staff in the Malawi site. In Malawi, the introduction of lay counsellors was perceived to have eased the workload of other providers, but lay counsellors reported inadequate support. Both countries had guidance on the minimum numbers of personnel required to deliver HIV services. However, patient loads per provider increased in both settings for HIV tests and visits by ART patients and were not met with corresponding increases in provider capacity in either setting. Providers reported this as a challenge. Although increasing patient numbers bodes well for achieving universal antiretroviral therapy coverage, the quality of care may be undermined by increased workloads and insufficient provider training. Task-shifting strategies may help address workload concerns, but require careful monitoring, supervision and mentoring to ensure effective implementation.