Maladaptive avoidance behaviour, a key symptom of anxiety-related disorders, prevents extinction learning and maintains anxiety. Individual personality traits likely influence avoidance propensity: high sensation-seeking may decrease avoidance, thereby increasing extinction, and neuroticism may have the reverse effect. However, research on this is scarce. Using a naturalistic conditioned avoidance paradigm, 163 women underwent differential fear acquisition to a conditioned stimulus (CSplus). Next, during extinction, participants could either choose a risky shortcut, anticipating shock signalled by CSplus, or a time-consuming avoidance option (lengthy detour). Across participants, increased skin conductance (SCR) acquisition learning predicted subsequent instrumental avoidance. Avoidance, in turn, predicted elevated post-extinction SCR and shock-expectancy, i.e., ‘protection-from-extinction’. Mediation analyses revealed that sensation seeking decreased protection-from-extinction—both for shock-expectancy and SCR—via attenuating avoidance. Neither sensation seeking nor neuroticism were related to acquisition learning and neuroticism was neither related to avoidance nor extinction. Transcranial direct current stimulation administered before extinction did not influence present results. Results highlight the important role of elevated avoidance propensity in fear maintenance. Results moreover provide evidence for reduced sensation-seeking and increased acquisition learning to be avoidance-driving mechanisms. Since approach-avoidance conflicts are faced by anxiety patients on a daily basis, strengthening sensation-seeking-congruent attitudes and approach behaviours may optimize individualized treatment.