Abstract The establishment of Swiss regional nature parks has been coupled with the need for sustainable regional development. Regional nature parks are one type of park in Switzerland, which may be considered analogous to the International Union for the Conservation of Nature's Protected Area Management Category V. These regional nature parks differ from other Swiss parks in their objectives and management. Some researchers and decision makers consider regional nature parks as instruments for bridging the development divide between economically advantaged and disadvantaged areas. The natural capital of regional nature parks may attract economic opportunities, generating agritourism and increasing regional agricultural product demands. The agricultural sector is especially vital for these regions. Regional park status may cause economic benefits through the intensification of agritourism or increasing sales of regional labeled products. Accordingly, our study examines the effect of gaining regional nature park status on farm earnings. For this purpose, we used agricultural earnings submitted to the Old Age and Survivors' Insurance System in regional nature parks established between 2010 and 2013 and compared them with the agricultural earnings of non‐regional park areas in Switzerland. We hypothesized that regional nature park status had no effect on the agricultural earnings of farmers inside a park. Employing causal analysis methods (i.e., matching in combination with a difference‐in‐difference estimator), we analyzed the regional nature park effect on agricultural earnings at the national, regional, and individual levels. The results show that for most regional nature parks, regional park status had neither statistically significant positive nor negative effects on agricultural earnings. As we included most of the parks belonging to one park category (regional nature parks), we extended our results to that entire category. Our results serve as a basis for policymakers and park managers to adapt current activities and design and implement measures to enhance the economic situation of farmers in these regional parks.