This study primarily aims to theoretically examine and empirically verify the effects of founding CEO characteristics on alliance formation in early-stage firms, based on a social network perspective. The social network perspective provides a theoretical foundation explaining that network relationships formed and attracted by a specific actor influence the actor's trust and legitimacy and can serve as an opportunity set for future strategic decision-making. In this context, this paper focuses on the founding CEO's personal experience and external visibility, develops a theoretical background, and formulates corresponding hypotheses. More specifically, research hypotheses were designed with the following independent variables: the founding CEO's pre-founding tenure, number of prior employers, large-firm work experience, and media exposure representing the CEO's external visibility. To test these hypotheses, this study constructed panel data for 116 new venture firms from 1998 to 2004, conducting empirical analysis with 406 research observations. The results confirmed that the founding CEO's pre-founding tenure and number of prior employers had positive effects on alliance formation in early-stage firms. Additionally, the founding CEO's media exposure was also verified to have significant explanatory power for alliance formation. Therefore, this study suggests that the founding CEO's pre-founding experience and external visibility can serve as important factors in the formation of alliances by early-stage firms.