Several studies have focused on stable personality traits as antecedents of career adaptability, but few have investigated more dynamic aspects of personality in relation to career adaptability. Recent theories on personality such as Whole Trait Theory (Fleeson, 2015) recognize that traits are often aroused in one situation but not in another (Allport, 1937), and that individuals are more or less flexible in responding to different situations. This flexibility is defined as within-person variability in personality. In the present paper we integrate Whole Trait Theory and Career Construction Theory (CCT, Savickas, 2005) – the latter stating that flexibility is a key antecedent of career-adaptability – and hypothesize that career-adaptability can be predicted by within-person variability in personality descriptions (Lang et al., 2019). In a sample of business administration students (N = 452) we found that, over and beyond effects of average trait levels, within-person variability in personality descriptions positively predicted career adaptability. Our findings have important theoretical and practical implications.