Purpose: This study aims to understand of the role that teacher entrepreneurial behavior plays in developing teacher professional capital. The extant concepts around school leadership mostly encompass the transformative and instructional roles of school leaders in managing, mobilizing and supporting teachers for student achievement. However, school leadership has not focused strongly on promoting innovation and risk-taking for schools in a knowledge economy. As a timely promising response to the increasingly demanding and competitive school context, teacher entrepreneurial behaviour (TEB), which emphasizes teachers' willingness to take risks and be daring, has started to gain recognition in the school leadership literature, yet a nuanced understanding of TEB's potential impacts on schools is lacking. Design/methodology/approach: Based on a combined consideration of institutionalized recognition and expert judgement, this study identified three innovative entrepreneurial teachers/teacher groups that had won the most competitive teaching award in Hong Kong. Employing a multiple-site case study design, this study conducted semi-structured interviews with 23 informants and collected supplementary school documents and records. Findings: This study found that TEB enables the implementation of innovation and promotes cross-subject alignment. It cultivates trusting and coherent relationships among teachers. Teachers with TEB scaled up innovation among other teachers. Furthermore, entrepreneurial teachers enhance school attractiveness by creating competitive advantages. Originality/value: This analysis showed that TEB enables formal and informal school leaders to bring forth critical school outcomes. This study elaborates how TEB enhances teachers' professional capital through building trusting and coherent relationships. It also adds to the research on school innovation by demonstrating that TEB fosters teachers' capacity for bottom-up innovation in the community.