When integrating sustainability, companies are often overlooking the changes needed in their organisational culture. This hinders organisations’ core business to efficiently embed sustainability and dooms corporate sustainability initiatives to be superficial. A possible solution is for organisations to develop a sustainability- oriented organisational culture that engages employees with the sustainability change and that develops a leadership supportive of the engagement of their employees. As a result, this thesis aims at exploring how organisations can change their organisational culture in order to fully integrate sustainability by engaging employees and managers. Specifically, it studies how employee engagement can contribute to transforming organizational cultures to fully embed sustainability. Additionally, this paper analyses how managers can support employee engagement with sustainability. The thesis conducts a literature review to set the theoretical foundations; it further resorts to semi-structured interviews and document analysis conducted in a Swedish public company, which has begun to integrate sustainability into its culture. The study finds that organisations’ cultures are being changed at the artifact levels and, partially, at the values and beliefs level of their cultures. Additionally, the thesis establishes that organisations are failing to create the conditions for employee engagement. It finally shows that leadership in companies is not efficiently supporting the engagement of employees to integrate sustainability into their culture.