The resource-based view of entrepreneurial networking demonstrates how relationships are formed instrumentally through the goal-driven decision-making of causation. At the same time, evidence shows that under conditions of uncertainty, entrepreneurs’ networking follows the non-predictive decision-making of effectuation. However, little is known about how entrepreneurs combine these two logics, that is, causation and effectuation, for opportunity development. This study identifies four hybrid combinations of causal and effectual networking behaviour. The outcome of this hybrid networking is a synergistic effect on opportunity development. The study contributes to the entrepreneurial effectuation research, the studies on entrepreneurial networking, and the literature on entrepreneurial opportunity.