This is the first empirical research in Hong Kong to examine the impact of social entrepreneurship training on disadvantaged young peoples’ career competence including their self-perceived employability, entrepreneurial knowledge, skills and intent, and their psychosocial development including their self-esteem, resilience, and career-linked self-efficacy. The subjects of this research were in-school youths and school drop-outs who joined the three waves of “Social-Up Youth Entrepreneurship Programme” including social entrepreneurship training (T1), internship (T2), and a pre-incubation project funded by a Charities Trust in Hong Kong. This research included a quantitative part, that is, questionnaires, and qualitative part, that is, focus group and individual interviews. At the time of data analysis, 100 disadvantaged young people joined the program at the baseline measure (T0). Only 77 and 31 could be matched and sufficient enough for data analysis at T1 and T2, respectively. The results demonstrated that social entrepreneurship training is positive and promising to enhance disadvantaged young peoples’ sense of self-worth and resilience, their entrepreneurial knowledge and skills, and overall self-perceived employability. The impact of the interactive and experiential-oriented social entrepreneurship training was the most significant. The impact of the internship was influenced by the extra burdens added to in-school youths. Because of its potential positive effects, further examination is required. Young people were found to have weak proactivity and flexibility in work, thinking, and interpersonal and communication skills, and the early introduction of curriculum-based youth entrepreneurship training in secondary schools is highly recommended.