This chapter examines the potential for integrating excess heat (EH) into district heating systems (DHS), highlighting its technical, economic, and functional benefits. The recovery and utilization of EH, typically generated as a byproduct of industrial, commercial, and residential processes, offers a cost-effective way to enhance resource efficiency, reduce operational costs, and improve the stability of DHS operations. By diverting waste heat into DHS, operators can reduce reliance on conventional energy sources, lowering heat generation costs while also decreasing greenhouse gas emissions. Examples of successful EH integration are presented, showcasing benefits such as improved energy security and a more resilient heat supply, especially during peak demand. However, despite these advantages, this chapter identifies several challenges, including opaque contracts between DHS operators and industries, concerns over heat supply reliability, and regulatory barriers, such as restricted third-party access to DHS networks. These issues hinder the broader adoption of EH utilization. To address these barriers, this chapter advocates for a comprehensive approach involving policy support, technological innovation, and infrastructure upgrades. Financial incentives, such as feed-in tariffs, along with advancements in heat pump and thermal storage technologies, are key to improving the efficiency of heat recovery. Additionally, upgrading DHS infrastructure is necessary to accommodate new heat sources. Collaboration among stakeholders is essential for fostering the conditions needed to successfully integrate EH into DHS, ultimately contributing to more sustainable and economically viable energy systems.