Expanding and sustaining B2B relationships is crucial for the survival of SMEs in international business. The language choice of SME decision-makers can support social interaction and improve common understanding. Yet, little is known about how decision-makers’ language background influences their sensemaking of international business relationships. Based on a five-year longitudinal study in 22 Finnish international small firms, this study captures three phases of the B2B relationship process, in which the influence of decision-makers’ language background is found in terms of their making sense of potential relationship value, knowledge sharing, and deciding on relationship continuity. The findings provide evidence that decision-makers initiate a business relationship with a particular buyer/supplier to increase knowledge sharing, which is facilitated or hindered by decision-makers’ language-based affinity and linguistic identity.