Purpose: Implementing a new organizational strategy effectively nowadays is said to require open strategizing practices. The purpose of this paper is to examine the adoption of three intertwined open strategizing practices in conjunction with a transformational leadership style towards effective strategy implementation. Design/methodology/approach: The study was conducted within 37 geographically dispersed locations of a Dutch governmental organization. The top managers and senior managers were surveyed at two points in time (n T1 = 548; n T2 = 414) and group interviewed at T2. Exploratory factor and linear regression analyses were performed. The qualitative data pertaining to the specific way in which leaders can impact the relationship between open strategizing practices and strategy implementation was analyzed using the Gioia methodology. Findings: As hypothesized, transformational leadership moderates the positive relationship between open strategizing practices and effective strategy implementation. This moderating effect was corroborated through the interview data in which the managers stressed the need for “intrinsically motivated” and “empowering” leaders to effectively support the adoption of their own locally-developed location strategy, as part of the overall strategy. Research limitations/implications: Despite the timely focus on the three intertwined open strategizing practices, the findings are only based on the perceptions of the various top and senior managers employed by one Western public sector organization. Practical implications: Top and senior managers who need to improve their organization's strategy implementation can apply the here tested three open strategizing practices. They should also be aware of the key role of transformational leadership. Originality/value: The authors contribute to the “open” strategy-as-practice domain by showing how top and senior managers' transformational leadership style supports the beneficial effects of adopting the three practices.