Trust in science is essential for the adoption of science-based advice, as it supports belief updating grounded in empirical evidence. Yet, little is known about the psychological mechanisms and boundary conditions under which trust in science promotes individual belief updating. The present research reports a preregistered experimental study (N = 1,305; general population) examining how trust in science interacts with source expertise and evidence direction to shape belief updating in the domain of acupuncture. Using a mixed 2x2x2 design, participants first reported their initial acupuncture-related beliefs and were then presented with scientific evidence—in the form of four brief study summaries—that was either conclusive or diverging (i.e., evidence direction factor; between-subjects). In addition, this evidence was attributed to either high-expertise or low-expertise scientists (expertise factor; between-subjects), experimentally manipulated via author descriptions. Beliefs were assessed a second time following the manipulation (within-subjects factor). Results showed that evidence attributed to high-expertise scientists elicited stronger belief updating than evidence from low-expertise scientists. Moreover, trust in science played a moderating role depending on expertise and evidence direction: Compared to all other groups, individuals with higher trust in science updated their beliefs more strongly when the evidence was conclusive and came from high-expertise scientists. In contrast, when these credibility cues were weak, trust in science did not promote belief updating. These findings suggest that trust in science supports an adaptive pattern of information processing: It facilitates belief change in response to credible evidence while guarding against uncritical acceptance of inconclusive information from unreliable sources.