According to the literature, avoidant personality disorder (APD) is often overlooked in research on personality disorders. In the present study, patients with APD were compared to patients with borderline personality disorder (BPD) with respect to emotional dysfunction. Emotional dysfunction was operationalized through the Affect Integration Inventory. Sixty-one patients receiving treatment at specialized outpatient hospital facilities for either BPD (n = 25) or APD (n = 36) (Diagnostic and Statistical Manual of Mental Disorders, fifth edition) were included in a cross-sectional study. Supporting our expectations of no difference in the global capacity for affect integration between groups, the estimated difference was 0.00 (95% confidence interval [CI] [−0.53, 0.53]). On the other hand, the expected increased dysfunction in APD regarding Expression could not be confirmed. Furthermore, problems with specific affects distinguished the groups; integration of Interest was worse in APD (p = 0.01), whereas integration of Jealousy was worse in BPD (p = 0.04). In terms of prototypical modes of experiencing affects, APD was characterized by decreased access to the motivational properties of Interest (p < 0.01), while BPD was more driven by Interest (p < 0.01), Anger (p < 0.01), and Jealousy (p = 0.01). In conclusion, even though the two disorders are characterized by similar overall levels of emotional dysfunction, they differ systematically and predictably regarding specific affects and modes of experiencing. These findings carry implications for the understanding of emotional dysfunction in APD and BPD, suggesting specific areas of emotional dysfunction that could be targeted in tailored psychotherapeutic interventions.