This study examines predictors and outcomes of intra‐individual mood variability in the workplace. During a 3‐month weekly study, we collected data on personality (extraversion and neuroticism), positive and negative workplace mood, and job performance from 357 participants. Path analysis revealed a positive relationship between neuroticism and intra‐individual variability in negative mood, which in turn predicted intra‐individual variability in performance. Results contribute to understanding between‐person differences in intra‐individual mood variability, and they suggest expanding the mood – performance relationship from a static perspective to an intra‐individual dispersion perspective. From a practical point of view, our results identify neuroticism as a potential risk factor for unstable performance, but they also give room for fostering predictable performance.Practitioner points Individuals with higher neuroticism may be prone to fluctuations in negative mood at work and indirectly to inconsistent performance – this highlights the necessity of personality assessment in both personnel selection and development. Interventions aimed at stabilizing mood can be an effective lever for stabilizing work performance.