Emerging adulthood is a developmental stage characterized by ambiguity and uncertainty, yet it is also marked by perseverance and goal-directed determination. One salient trait during this period is grit, defined as the sustained passion and persistence toward long-term goals, such as successfully passing a licensure examination. This study proposed and tested a model examining the relationships among grit, tolerance for ambiguity, and intolerance of uncertainty among emerging adults preparing for their psychology licensure examination. A total of 1,180 licensure examinees completed standardized measures of grit, tolerance for ambiguity, and intolerance of uncertainty one month before their psychometrician licensure examination. Results revealed that grit significantly predicted higher tolerance for ambiguity, indicating that individuals who persist toward their goals are better able to manage ambiguous situations. Furthermore, tolerance for ambiguity was found to reduce both dimensions of intolerance of uncertainty—inhibitory and prospective anxiety. These findings suggest that developing grit and tolerance for ambiguity plays a crucial role in mitigating cognitive and behavioral forms of anxiety among emerging adults facing high-stakes professional challenges.