Perceived norms attached to public transport travel significantly reinforce mobility inequalities. Such mobility inequalities contribute to social exclusion, particularly among vulnerable groups such as older adults. Thus, understanding the antecedents of older adults' social exclusion behaviour is vital in advancing knowledge and promoting social sustainability. We proposed an integrated model and included 384 older adults from diverse socio-demographic backgrounds in Pakistan, examining the impact of social and personal norms of public transport use on social exclusion. Results revealed that social norms of public transport use played an essential role in shaping older adults' social exclusion directly and indirectly via personal norms. Perceived accessibility further moderated the effect of social and personal norms on social exclusion. The antecedents of personal norms (i.e., awareness of consequences and ascription of responsibility) were analyzed based on the Norm Activation Model. This study suggests that the prevalent norms supporting public transport use can act as a complementary policy for promoting independent mobility and, thus, social inclusion among older adults. Transport policymakers and social researchers can consider the findings to develop healthy ageing societies.