The Malaysian public sector is oversaturated with comprehensive procurement procedures. These measures aim to deter unwarranted behaviours from public officers. Nevertheless, there have been recurring irregularities over the past decade in Malaysian local authorities, including work delays, non-compliance with regulations, wasteful purchasing, substandard workmanship etc. This study aimed to investigate factors undermining rationality in public procurement decision making from the cognitive perspective. The cognitive and behavioural science literature was reviewed systematically, focusing on procedural rationality to develop a predictive model of procurement irregularities. This research adopted a quantitative approach. A total of 289 datasets were collected from the procurement officers of Malaysian local authorities and analysed using the Partial Least Square Structural Equation Modelling technique. The empirical findings showed that work experience, prior knowledge, and accountability correlate directly with procedural rationality in procurement decision-making, which would impact the procurement outcome. The research offered insights into the decisionmaking behaviour of procurement officers from the cognitive psychology perspective. From the managerial standpoint, public procurement procedures should incorporate the elements of accountability, experience, and prior knowledge as part of the quality assurance and control measures.