Background The coronavirus disease 2019 (COVID-19) pandemic severely afected global food security, but analyses of its impact on the cost and afordability of a healthy diet are limited. This study examines the immediate efect of the COVID-19 pandemic on the cost and afordability of a healthy diet among urban households in Bangkok, Thailand and Manila, the Philippines. Methods We used ofcial food price and household income and food expenditure data from the national statistics ofces. The cost of recommended diet (CoRD) method was employed to assess the minimum cost of a healthy diet, following the healthy diet recommendations provided in the national food-based dietary guidelines of the specifc countries. Regression discontinuity design was estimated to determine the COVID-19 efect on food prices and scenario analysis done to determine the efect of reduced food budgets with and without government relief programs. Results The results show that the average cost of the recommended diet was US$ 1.55 per person/day in Bangkok and US$ 3.76 in Manila (2019 prices in purchasing power parities) immediately before the pandemic. This diet is generally afordable for all households in Bangkok, but only for 37% of households (4.98 million people) in Manila, indicating much higher poverty in the latter. The pandemic and associated government measures decreased the cost of the recommended diet with 6.5% in Bangkok (p=0.001) but not in Manila (p=0.167). Assuming contractions in people’s food budgets of 15–20%, the recommended diet became unafordable for 0.08–0.12 million people in Bangkok and 6.32–7.73 million people in Manila during the pandemic. Government relief largely compensated for this loss in Bangkok, but relief payments in Manila were not enough to compensate the efect. Conclusion These results show that the main efect of the COVID-19 pandemic on the afordability of healthy diets was through the efect on reduced incomes of the poor rather than through prices. Government relief measures should target low-income households to give them the means to purchase healthy food items.