This paper focuses on the development of a bioplastics innovation niche as an important sector of the bio-based economy and a viable solution to promote sustainable long-term growth. Relying on the Strategic Niche Management framework, the following niche mechanisms are analysed: (1) convergence of expectations, (2) learning processes, and (3) networking with powerful actors in the sector. We conducted a comparative analysis, looking at Italy and Germany, two frontrunner countries in the bioplastic production who have enacted divergent policies in support of this sector. The comparative perspective has brought some interesting insights into the maturity level of the two respective niches, as well as into the emerging architectural properties of the underling social networks. Core findings show a general high level of expectations in the bioplastics sector in both countries, whereas key elements undermining the niche development refer either to the lack of policy support or to the changing and unstable institutional and regulatory framework. Regarding the architectural structure, the Italian network of actors was largely characterized by an active exchange of knowledge among firms, whereas the German network was characterized by the presence of several institutional actors actively participating in knowledge flows. This last result relates, in the authors' view, to the different policy strategies followed by national governments in the two countries: the German case being characterized by large public investment in R&D, whereas the Italian case is mostly characterized by demand side policies that effectively created a market for bioplastic shoppers.