Surge capacity—the ability to acquire additional workers and resources during unexpected increases in service demand—is often perceived as a luxury. However, the COVID-19 pandemic necessitated an urgent expansion of surge capacity within health systems globally. Health systems in Bangladesh, Nepal, and Sri Lanka managed to scale up their capacities despite severely limited budgets. This study employs a mixed-methods approach, integrating qualitative interviews with quantitative data analysis, to propose a comprehensive framework for understanding Human Resources for Health (HRH) surge capacity from 2018 to 2021, termed ARRAS: Anticipate, Recruit, Retain, Adapt, Sustain. We present national-level data to demonstrate how each country was able to maintain their per capita health care workforce during the crisis. Interviews with key informants from each country reinforce the ARRAS framework. Quantitative data revealed ongoing increases in doctors and nurses pre- and post-pandemic, but no country could rapidly expand its health workforce during the crisis. Qualitative findings highlighted critical strategies such as pre-crisis planning, financial incentives, telemedicine, and re-skilling the workforce. Despite adaptive measures, challenges included inadequate funding, poor data systems, and coordination issues. This study underscores the necessity for robust, long-term strategies to enhance surge capacity and better prepare health systems for future crises.