Purpose: This service aims to foster harmony in a multicultural community in the city of Solo as a concrete step to increase peace and support the achievement of the Sustainable Development Goals (SDGs). Theoretical Framework: This study uses a cultural integration thinking framework and a participatory approach to building social harmony. The focus is on developing an understanding and appreciation of cultural diversity, as well as increasing positive interactions between ethnicities and religions to create an inclusive environment. Methods: This service uses a participatory approach involving a variety of local stakeholders, including ethnic and religious communities, local governments, and community institutions. Activities include organizing intercultural dialogue workshops, cultural diversity training, and public campaigns to promote tolerance and peace. Results and Conclusion: The results of this service show an increased awareness of cultural diversity and appreciation for differences among the people of Solo. Inter-ethnic and religious interactions are increasing, creating a stronger foundation for social harmony. In conclusion, participatory and integrative approaches are effective in building harmony in multicultural societies to support peace and sustainable development. Implications: This service has a positive impact by increasing tolerance, reducing social conflicts, and strengthening social cohesion in the city of Solo. The impact is also seen in increasing community participation in local development activities and achieving related SDGs targets. Originality/value: Its uniqueness lies in its participatory approach that actively involves all relevant parties, as well as focusing on cultural integration as the main foundation for the development of sustainable social harmony in a multicultural environment such as the city of Solo.