In marketing channels, the unethical pro-organizational behavior of manufacturers’ salespeople can negatively impact channel partners and even the entire channel system. However, research on the antecedents and consequences of such behavior remains limited. Drawing on the individual ethical decision-making model and attribution theory, this study constructs a conceptual model to examine the antecedents of unethical pro-organizational behavior among manufacturers’ salespeople and its impact on distributors’ trust. We empirically tested the hypotheses by collecting primary survey data from matched triads of manufacturer sales managers, manufacturer salespersons, and distributor managers. This study finds that deontological factors-manufacturer ethical values and relational norms-can mitigate unethical pro-organizational behavior, while teleological factors-manufacturer outcome control and relative dependence-respectively promote and inhibit such behavior. Such unethical behavior by salespeople reduces distributors’ trust in the manufacturer, and distributors’ attribution moderates this negative effect. Finally, this study concludes with an analysis of the theoretical significance of the research and its practical implications for channel management practices.