Purpose: The purpose of this paper is to identify the role intermediaries can play in an small to medium-sized enterprise's (SME's) pursuit for corporate sustainability with a focus on eco-innovation. The research identifies drivers and barriers for eco-innovation, and highlights effects induced through collaboration between SMEs and local authorities, on the one hand, and consultancies, on the other. Design/methodology/approach: This paper is based on an exploratory qualitative interview study among German SMEs of the metal and mechanical engineering industry that have participated in "Ecoprofit", an intermediary based program that aims at introducing organizations to the concept of sustainable development through implementation of eco-innovations. Findings: The key findings are that first, the proactive approach by a public intermediary (here local authority) is one essential push factor to trigger eco-innovations in SMEs with low absorptive capacity. Second, it is found that SMEs may need facilitation for eco-innovation from different types of intermediaries (public and private) with different levels of support, which can range from customized and individual to more loosely held support, such as networks. Originality/value: This study discusses the challenges of corporate sustainability with a focus on eco-innovations for SMEs and proposes a "complex intermediary" consisting of a local authority and consultancies as one means to engage SMEs in sustainability. Moreover, it focuses on SMEs in the B2B context, organizations that are often overlooked despite their vast impact. Furthermore, by using a single industry approach, in-depth findings for the metal and mechanical engineering industry are presented.