Background: Pain is frequently under-assessed in hospitalised older adults with cognitive impairment. Evidence indicates low rates of pain assessment initiation and inappropriate tool use, contributing to suboptimal pain management and poorer health outcomes. Aim: To evaluate the feasibility, utility, and impact of implementing the PainChek® app as part of standard care for patients with cognitive impairment in an acute medical ward. Methods: This implementation study comprised three phases: 1) a 15-minute staff training session delivered by a nurse champion, including a train-the-trainer component, 2) app implementation over six months for eligible patients, and 3) evaluation using post-training surveys, post-implementation surveys, individual interviews, compliance audits, and app usage data. Data were triangulated to assess acceptability, appropriateness, and feasibility. Results: A total of 546 pain assessments were recorded over six months (mean three assessments per day). Most assessments (96.9%, n=529) indicated no pain, with the automated video function used in 87.0% (n=475) of assessments. Of the 35 participants completing the training evaluation, 88.5% (n=31) reported confidence in using the app. Post-implementation feedback from 22 participants indicated borderline acceptability and appropriateness, and poor feasibility. Key barriers included time constraints, workload pressures, patient-related factors, and concerns regarding tool reliability, consistent with compliance audit findings. Conclusions: Findings highlight the need to strengthen clinicians’ understanding of pain assessment in cognitively impaired older adults alongside technical training. This study identifies barriers to integrating digital innovations into routine care and provides practical insights to support effective, technology-enabled pain assessment in acute settings.