Experimental studies to date have demonstrated the agronomic and environmental benefits of intercropping, making it a key diversification method for reducing chemical inputs in agriculture. However, intercropping is still a niche practice in European cropping systems, particularly for arable crops. Few studies have focused on farmers’ perspectives or used farm data to assess the on-farm performances of intercropping. Here, we present an analysis of data collected from farms of the DEPHY network, a demonstration farm network that aims to show that pesticide use can be reduced through changes in farming practices. We focused our study on four main species in France: winter wheat (Triticum aestivum L.), winter barley (Hordeum vulgare L.), pea (Pisum sativum L.) and rapeseed (Brassica napus L.). We carried out paired comparison tests between sole crops and intercrops for each species (16 pairs for winter wheat, 12 for winter barley, 15 for peas and 31 for rapeseed) to compare the use of pesticides (herbicides, fungicides, insecticides and all pesticides combined), mineral nitrogen fertiliser and the gross margin. We showed that pesticide use was reduced on average by 40–50% in the case of wheat- and barley-based intercrops compared with sole wheat and barley crops, respectively. Pesticide use for peas was reduced by 72% on average. Nitrogen fertiliser use was also reduced by up to 38% for wheat. On the other hand, in the case of rapeseed, which is mainly intercropped with unharvested companion plants, we found no significant differences in pesticide or fertiliser use between the sole crops and intercrops. This suggests that farmers must choose companion plants carefully depending on their objectives and desired services. Finally, our findings show that intercropping negatively affects gross margins for wheat, but gross margins are maintained for barley-, pea- and rapeseed-based intercrops compared to sole crops.