Farmers are innovators and experimenters and not just adopters of introduced technologies. The innovations developed by farmers could complement the highly promoted externally driven technologies in addressing the numerous challenges facing agriculture. The aim of this paper was to identify outstanding innovations developed by smallholder farmers in northern Ghana, and prioritize the high potential ones for further scientific validation or dissemination. Using an innovation contest that rewards farmers’ creativity, we identified 29 promising innovations. Additionally, 19 innovations were scouted through a household survey. The innovations are largely extensive modifications of existing practices or combinations of different known practices in unique ways to save costs or to address crop and livestock production constraints. While some of the identified innovations can be recommended or disseminated to other farmers, most of them may require further validation or research. However, validating all of these innovations will be very expensive and time-consuming. We propose the multi-criteria decision-making analysis (MCDM) as a simple method to prioritize farmers’ innovations. Using this method, we find that among the most promising innovations are those involving the control of weeds, pests and diseases using plant residues and extracts, and the treatment of livestock diseases using ethnoveterinary medicines. We briefly explain the six most highly ranked innovations. This case study from northern Ghana provides further proof that smallholder farmers develop diverse and spectacular innovations to address the myriad challenges they face, and these need to be recognized and promoted. We also conclude that contest and MCDM are useful methods that can be applied in unearthing and prioritizing farmer innovations, respectively.