These comprehensive guidelines guide partners in researching and addressing the impact of heatwaves on older adults. Developed through primary, secondary, and tertiary research, they identify challenges and unmet needs in heatwave management. A co-design framework ensures organizational change management by fostering clear vision, leadership, supervisory support, and goal setting. This collaborative approach involves stakeholders for effective communication and engagement, empowering older adults and professionals to build capacity, improve decision-making, and raise awareness. Tailored training content, actionable strategies, and evaluation methods make these guidelines effective tools for adoption across Europe.