Sustainable entrepreneurs are a relatively new breed of entrepreneurs who use innovations to tackle environmental and societal challenges. Because their ventures focus on sustainable value creation rather than financial performance, crowdfunding is a novel method of fundraising that helps these sustainability-oriented ventures get the capital they need through campaigns conducted on online reward-based crowdfunding platforms such as Kickstarter and Indiegogo. There is adequate research about their funding, but little investigation exists about how they commercialize their ventures post-campaign. We believe that the social capital theory provides a promising lens to deeply understand this period. In particular, this paper argues that social capital arising from outside of the crowdfunding platforms (i.e. external social capital) has a strong influence on the overall post-campaign commercialization activities, which include the broad categories of continued production, logistics and marketing. A qualitative abductive case study research with five crowdfunded ventures offering sustainability-oriented products is conducted in order to derive a deeper understanding about this niche. Findings are compared with current literature in order to reveal that two particular dimensions of social capital play the most crucial role in post-campaign commercialization- External Relational and External Cognitive. These dimensions involve different relational and cognitive facets that come into play between the sustainable entrepreneurs and the external social capital, facilitating the post-campaign commercialization process.