To extend the research on interactions‐based justice and integrate it with the research on trustworthiness, the present article examines the role of informational and interpersonal justice in co‐worker interactions for task accomplishment. Based on social exchange theory and fairness heuristic theory, the two justice dimensions would trigger different types of responses based on the principle of reciprocity and how they manage different types of uncertainties in a work relationship. As a result, they lead to different outcomes in the context of two co‐workers having a disagreement about work. It was hypothesised that informational justice is related to acceptance of the co‐worker's view primarily through perception of ability‐based trustworthiness, whereas interpersonal justice is related to satisfaction with the co‐worker primarily through perception of benevolence‐based trustworthiness. A survey of employees and a simulation study showed that the effect of informational justice on acceptance of the co‐worker's view is mediated more by ability‐based trustworthiness than by benevolence‐based trustworthiness, whereas the reverse is true for the mediation of the effect of interpersonal justice on satisfaction with the co‐worker. Theoretical implications are discussed concerning the differentiation of the two highly correlated justice dimensions, together with practical implications regarding their relative usefulness.