The agriculture and livestock sectors face several challenges related to achieving the current EU environmental objectives. Two of the major policy goals include reducing greenhouse gas emissions and ensuring an increased share of nitrogen, phosphorus, and potassium from renewable sources. Farmers are continuously seeking to adopt technologies and solutions to ensure sustainable food production systems. Adoption of innovation at the farm level based on a circular economy may improve resource efficiency, allow the reuse and recovery of nutrients, and reduce the negative effects of emissions on soil, water, and air. This study aims to identify the factors affecting the adoption of several circular agronomy solutions using a semi-structured questionnaire on a sample of farmers in four EU countries: Spain, Austria, the Czech Republic, and Italy. The results indicated that acceptance of proposed circular innovations is closely related to farmers’ environmental objectives, experience, university education, previous experience in innovation adoption, and environmental attitudes. Additionally, institutional support plays a significant role in adoption decisions. Factors affecting adoption decisions may assist policymakers in designing more specific and efficient measures to help farmers meet their current social needs and environmental challenges.