ABSTRACT Intercropping has been widely proposed as a strategy to improve the sustainability and resilience of agricultural systems. Grain legumes are particularly suited for intercropping due to their functional diversity and capacity for biological nitrogen fixation; however, challenges remain to design efficient intercropping systems centred on the grain legume species. Notably, varietal differences within the legume species may strongly influence competitive interactions and, consequently, intercrop performance. In this study, we evaluated the performance of twelve pea ( Pisum sativum L.) varieties in pure stands but also intercropped either with barley ( Hordeum vulgare L.) or lentil ( Lens culinaris L.). The experiment was conducted during two contrasting growing seasons in small plots in Switzerland. We assessed grain yields of each species, as well as intercropping effects on lodging and disease development. The main results showed that barley was too competitive, but intercropping with lentil allowed to maintain pea yield during a bad year. Intercropping generally provided advantages in terms of yield stability, lodging control, and disease management. Pea–barley intercrops effectively limited lodging and significantly reduced ascochyta blight severity, but barley proved highly competitive, leading to reduced pea yields. In contrast, pea–lentil intercrops allowed peas to maintain yields under unfavourable climatic conditions and led to moderately reduced disease development, although productivity was more variable. Strong varietal effects were observed, and promising pea varieties for intercropping were identified. These results highlight the importance of jointly selecting associated crops and pea varieties to maximize the benefits of intercropping. Optimizing such systems requires an integrated approach that combines varietal choice, sowing density management, and consideration of downstream value‐chain opportunities.