Despite growing interest in the clinical and theoretical implications of psychological safety, particularly from a Polyvagal Theory (PVT) perspective, there has been a lack of empirically validated measurement tools for this construct. The main aim of this study was to evaluate the reliability and construct validity of the Neuroception of Psychological Safety Scale (NPSS), a 29-item self-report scale designed to measure psychological safety, conceptualised from a PVT perspective. This study also explored how individuals define "feeling safe". A total of 423 participants completed an anonymous online survey. The sample consisted predominantly of undergraduate psychology students (n = 353), while the remaining participants were members of the New Zealand general population. An exploratory factor analysis was conducted to examine the factorial validity of the NPSS, while construct validity was evaluated through correlations with measures of theoretically related constructs. Internal consistency was assessed using Cronbach's alpha (α) and McDonald's omega (𝜔). The NPSS demonstrated good internal consistency and was found to have a three-factor structure consistent with that proposed by the scale's developers. Construct validity was evidenced by significant correlations in the expected directions with depression, anxiety, stress, negative affect, positive affect, difficulties in close relationships, awareness of physiological responses and traumatic life experiences. In addition, themes identified in participant definitions of safety aligned with the conceptualisation of psychological safety from a PVT perspective. Overall, the main findings of this study provide evidence that the NPSS is a psychometrically sound measure, supporting the use of the NPSS in clinical practice for measuring treatment outcomes and guiding intervention strategies, and in future research to advance the theoretical understanding of psychological safety from a PVT perspective.