Crowdsourcing platform (CP) enables online generation of open innovations, including new products, by prosumers as crowd (the Internet community) members for its clients (companies, non-profit organizations, individuals). The following goals are defined in the paper: (1) creating CP marketing concept for CPs developing open innovations, that combines characteristics of: the marketing orientation, collaborators, marketing research and marketing mix of the platforms; (2) verifying the possibilities of applying the proposed components of marketing mix in business practice, which are the core of the presented marketing concept for CPs. The article includes relevant literature studies as well as the analysis of marketing mix application in business practice by selected platforms and taking into account the research results that was carried out for 69 CPs in 2023. The final conclusion is as follows: the formulated research problem – How to apply marketing also with the use of marketing mix in activities of CPs developing open innovations? – has been solved and defined goals have been achieved in the paper.