Hypomanic traits are often assumed to enhance creative thinking, but empirical evidence is mixed. The present study assessed creativity in divergent thinking across a broad range of hypomanic traits. Participants (n = 468, including both healthy adults and individuals with bipolar disorder) completed Alternate Uses Tasks (AUT) in which they generated novel uses for common objects. Independent raters scored each response for creative quality, considering both originality and usefulness, yielding two metrics per participant: mean creativity (average idea quality) and maximum creativity (average of the most creative ideas). Inhibitory control was measured using a Stroop color-word task. Regression analyses showed that higher hypomanic traits predicted greater fluency (i.e., more uses generated) but lower creative quality in AUT (both lower mean creativity and lower maximum creativity). No evidence for a curvilinear (inverted-U) relationship was found. Moreover, higher hypomanic scores were associated with more interference errors in Stroop performance, and greater Stroop interference correlated with lower creativity. Mediation analysis indicated that Stroop interference partially accounted for the negative hypomania–creativity link. These findings suggest that individuals high in hypomanic traits tend to produce many ideas, but those ideas are, on average, less creative—partly due to diminished inhibitory control. The results underscore the importance of measuring creative quality, not only fluency or originality, and considering executive functions when studying creative thinking in bipolar-spectrum populations.