Purpose - Drawing upon the theory of planned behaviour (TPB), the purpose of this paper is to examine the influence of managers attitude and other psychological factors on sustainability reporting (SR). In doing so, this paper aims to respond to calls for the use of previously untried theoretical approaches on the SR literature. Design/methodology/approach - The study uses a survey of top and middle-level managers of listed and non-listed companies in Sri Lanka. Data were analysed using a Partial Least Squares path model. Findings - The findings indicate that managers attitude towards SR, belief about stakeholder pressure, and their capacity to control SR behaviour influence their intention to engage in SR and, indirectly, actual corporate SR behaviour (in the context of listed companies). However, whilst managers of non-listed companies exhibit the intention to engage in SR, the lack of a relationship between intention and behaviour suggests that companies face barriers towards SR due to lack of actual control over the SR process. Religion, in the case of non-listed companies, and education, in the case of listed companies, has some degree of influence over managers beliefs. Research limitations/implications - The use of self-reported SR behaviour is a limitation but necessary to maintain anonymity of respondents. The low levels of self-reported SR correspond with past evidence on actual SR in developing countries. Practical implications - The results show that managers psychological factors are important in determining SR behaviour in companies. Specifically, this highlights the possible roles that regulators, professional bodies and companies can play in improving educational and cultural influences towards improving the level of SR. Originality/value - This is the first study to apply the TPB to understand SR behaviour by integrating psychological factors relating to managers belief, attitudes and perceptions.