Despite the mission of providing holistic education to nurture students’ sustainability competence, university education has faced criticism for failing to achieve this goal. Therefore, a curriculum-based Service-Learning (SL) Subject was developed and implemented for migrant children in East China and needy youth in Hong Kong to build their diverse developmental assets. Based on the positive youth development and strength-based approaches, multiple teaching and learning strategies and techniques are adopted in the SL subject. Moreover, after a review of the development and achievements of this SL subject over a decade, this chapter introduces the effectiveness evaluation of the SL subject from multiple perspectives (e.g., service providers, service recipients, and partnering organizations). It provides a comprehensive summary of the students’ learning experiences across seven aspects (e.g., contributions to intrapersonal and interpersonal development). To date, the SL subject has benefited more than 3,000 migrant children in China and 6,400 needy youth in Hong Kong, making a tremendous social impact in promoting educational and cultural exchanges and strengthening social capital and sustainability in the served schools and communities. In future, the SL subject will be continuously refined from various aspects to bring more significant benefits to youth and serve as a “model” for counterparts in mainland China and countries along the Belt and Road, aiming to sustain support for disadvantaged youth.