Finding ways to improve the service quality and consequently attract more passengers is a major concern for public transit officials worldwide. Given the fact that there is a glaring deficiency of service quality models in the literature, especially for developing nations, the present study develops interrelationships among service quality factors of Metro Rail Transit System (MRTS) in Delhi, India. For this purpose, the study implemented an integrated Bayesian Networks (BN) and Partial Least Squares Structural Equation Modelling (PLS-SEM) approach on perceptions of 2390 passengers of Delhi Metro. Firstly, the study extracted 41 service quality indicators into eight service quality factors using principal component analysis. Secondly, the extracted factors were learnt in BN to achieve the most robust network structure. Thirdly, the robust BN structure was tested and analysed in PLS-SEM to develop a service quality model. The integrated methodological approach has facilitated in identifying hidden interrelationships among service quality factors through a systematic manner. The developed model indicates ‘passenger ease’ as the most influential and ‘amenities’ as the least influential factors of overall service quality (OSQ). The OSQ index of 79.59 reveals the moderate satisfaction of passengers with Delhi Metro services. The study proposed several insights into the service quality improvements for Delhi Metro that must be focused and enriched for increasing Metro transit ridership. This knowledge of interrelationships among service quality factors can help transit officials in formulating effective strategies and investment plans accordingly to meet the passengers’ needs.