This study examines the changes in waste heat (WH) potential from existing and emerging hydrogen-based industries and their impact on district heating (DH) systems. Gällivare and Gothenburg, two Swedish municipalities with differing demographics, industries, energy needs, renewable potential, and climates, are assessed for their common role in the ongoing hydrogen-based industrial transition. Gällivare and Gothenburg are modelled using energy system optimization models, TIMES-City and the in-house City model respectively, and are assessed for 2050. In Gällivare, integrating WH from emerging hydrogen-based industries into DH could reduce electricity demand for heating by around 20 times, thereby freeing up power for the decarbonization of industry and transport. In the maximum WH scenario, DH’s share in heat supply reaches almost 100 %, reducing marginal heating costs by 22 % compared to the current level. In Gothenburg, recovered heat from electrolysis could meet up to 20 % of the annual heating demand. In general, Power-to-Heat technologies are preferred when WH availability is low. However, large-scale hydrogen production via electrolysis increases electricity grid congestion, leading to investments in combined heat and power plants to meet the demand for electricity locally.