Although stair-climbing intervals provide a simple mode of physical activity that can be easily carried out in naturalistic settings and incorporated into the daily lives of a significant proportion of the global population, addressing physical inactivity issues, very little research has focused on the psychological benefits of stair climbing. To address this, the current prospectively registered randomized controlled crossover trial tested whether brief bouts of stair climbing (6 × 1 min intervals) elicit immediate subsequent improvements in cognitive performance and mood in a sample of healthy young adults (final sample: n = 52, 50% female, age range 18–24 years), with consideration of sex, physical activity habits, and exercise intensity as potentially relevant variables. Compared to a no-exercise control session, following the stair climbing participants exhibited superior cognitive switching performance and reported feeling more energetic and happy. In addition, linear regression analyses linked higher stair-climbing intensity (indicated by heart-rate data) to faster response latencies. None of the effects depended on sex or physical activity habits, which implies that males and females can benefit irrespective of their current physical activity habits. Collectively, these results demonstrate that interval stair climbing can confer immediate psychological benefits, providing further evidence in support of stair climbing as a promising means to address physical inactivity issues. TRN: ACTRN12619000484145, Date of registration: 25/03/2019.