Recent research pointed at the potential of buyer–supplier collaborations for joint innovation generation. However, studies reveal mixed results. Since multiple contingency factors influence the results of cooperation, this study analyses different relationship patterns as a context for joint innovation generation and problem solving. A comprehensive model of buyer–supplier relationships is conceptualized drawing on social psychology literature. Based on a sample of 250 small and medium‐sized enterprises (SMEs) from the German machinery construction sector, buyer–supplier relationships are empirically classified into four distinct types. These then are related to the innovation outcomes. The results indicate that a relational context fosters joint innovation generation and problem solving. Interestingly, a high degree of formalization, if it is legitimated, can also lead to innovation. Sporadic superficial interactions as well as interactions dominated by tension hinder joint innovation generation, though. The results help managers to consider the potential innovative outcomes when making decisions about supplier cooperation.