Ultra-wideband (UWB) positioning systems offer promising solutions for monitoring dairy cow behaviour, but their performance in complex barn environments needs a thorough evaluation. This study assessed the TrackLab 2.13 UWB system (Noldus) in a commercial dairy barn, focusing on its accuracy and reliability for tracking cow movements and detecting proximities. We tested the system using stationary and moving tags that simulated cow movement. Positioning reliability varied widely for stationary tags, with central barn locations performing best. Stationary and moving tags satisfactorily complied with the manufacturer’s specified accuracy of 0.30 m. The system accurately detected 81.42% of cow proximities to fixed points, indicating its potential for studying social interactions and resource use. While challenges remain, particularly near barn perimeters, this UWB technology shows great promise for enhancing animal welfare monitoring and behaviour research in commercial dairy settings. These findings will help farmers and researchers utilise positioning systems more effectively, improving livestock management and welfare assessment.