Functions of innovation systems framework have established their value as tools for exploring sociotechnological transitions and economic development. Although the “seven functions” model has demonstrated its academic value across a vast literature, there have been few attempts to explore the role of the model in climate smart farming. Therefore, the aim of this study is to determine relative importance of functions of innovation system on cassava climate smart farming in Kenya. The study focused on the following seven functions of innovations; entrepreneurial activities, knowledge development and diffusion, search for guidance, market development and stabilization, resource mobilization and legitimacy development. Data were collected from 150 cassva farmers in Nyando Sub-County, Kenya. Data analysis deployed the Best-Worst scaling (BWS) choice method and expanded to include the multinomial logistic regression modelling. Results revealed that knowledge development, diffusion and resource mobilization were the functions of innovation systems ranked highest in terms of shared importance among the seven innovation functions. In fostering cassava innovations, their relative importance was knowledge development (19.17%), knowledge diffusion (18.86%) and resource mobilization (14.88%). Evidence from the multinomial logistic regression revealed that farmers chose knowledge development as most important innovation function to foster cassava innovations in the Nyando CSV.