Uncertainty is increasingly discussed during genetic counseling due to innovative techniques, e.g., multigene panel testing. Discussions about uncertainty may impact counselees variably, depending on counselors’ communication styles. Ideally, the discussion of uncertainty enables counselees to cope with uncertainty and make well-informed decisions about testing. We examined the impact of how counselors convey uncertainty and address counselees’ uncertainty, and explored the role of individual characteristics. Therefore, a randomized controlled experiment using videos was conducted. Former counselees (N = 224) viewed one video depicting a genetic consultation about multigene panel testing. The extent of counselors’ communication of uncertainty (comprehensive vs. the essence) and their response to counselees’ uncertainty expressions (providing information vs. providing space for emotions vs. normalizing and counterbalancing uncertainty) were systematically manipulated. Individual characteristics, e.g., uncertainty tolerance, were assessed, as well as outcome variables (primary outcomes: feelings of uncertainty and information recall). No effects were found on primary outcomes. Participants were most satisfied when the essence was communicated, combined with providing information or providing space responses (p = 0.002). Comprehensive information resulted in less perceived steering toward testing (p = 0.005). Participants with lower uncertainty tolerance or higher trait anxiety were less confident about their understanding when receiving comprehensive information (p = 0.025). Participants seeking information experienced less uncertainty (p = 0.003), and trusted their counselor more (p = 0.028), when the counselor used information providing responses. In sum, the impact of discussing uncertainty primarily depends on individual characteristics. Practical guidelines should address how to tailor the discussion of uncertainty.