The practice of collaborative innovation promises added benefits for the concerned stakeholders based on the capacity that the product of the knowledge, experience, and skills shared by the collaborating parties outweighs the sum of all the inputs. However, collaborations also carry the challenge associated with leadership, which is often established through informal influence. The paper presents the best practices for impactful informal leadership in collaborative innovation networks in project execution. The research is based on expert interviews with European start-ups, SMEs, large enterprises, and universities. The findings and recommendations focus on enhancing the impact of the innovative solutions once they are institutionalised in the organisations. The impact generally leverages the consequence of informal leadership, a naturally occurring phenomenon, emphasising the variability and reciprocity of leading, the meaning of strategic goals, and investing in human relations, and deeply contributing to the transition towards Industry 5.0 and Society 5.0.