Impaired working memory in response to social-evaluative stress might be a central cognitive mechanism underlying the persistence of mental health difficulties such as social anxiety. To investigate this, we developed the Socio-evaluative N-back Task (SENT), which can measure the impact of acute socio-evaluative stress on working memory (WM) performance. Moreover, we tested the SENT in a stratified sample with high (HSA) and low socially anxious (LSA) individuals (HSA = 30, LSA = 27, N = 57). Of the highly anxious individuals, thirteen were diagnosed with social anxiety disorder (SAD). The socio-evaluative stress condition, compared to a control condition, increased psychophysiological stress reactions, and reduced WM performance. Moreover, people with low anxiety displayed faster reaction times under socio-evaluative stress compared to a control condition. Conversely, individuals with high social anxiety demonstrated consistent reaction times regardless of whether they encounter a non-evaluative or socio-evaluative situation. This suggests that social anxiety is associated with a lack of differentiation between neutral and socio-evaluative situations. Additionally, this study indicates that the socio-evaluative N-back Task can be used to induce socio-evaluative stress responses while simultaneously measuring working memory and physiological stress responses.