Sheep scab, caused by infestation with the ectoparasitic mite Psoroptes ovis, is an endemic disease in the Northern Ireland (NI) sheep flock and constitutes significant economic and welfare burdens for the NI farming industry. Despite its endemic nature, historically, little research has been undertaken to support the control of the disease in NI. This study offers the first attempt to analyse the psychological and behavioural factors influencing farmers’ intentions to implement effective sheep scab control measures in NI. To achieve our objective, quantitative data from a sample of 126 sheep farmers were statistically analysed using an extended theory of planned behaviour approach in an ordered logistic regression modelling framework. Our analyses showed that sheep scab remains an issue of concern in Northern Ireland. The attitudes of the farmers, as well as perceived behavioural control, emotional effect, membership of Business Development Groups (BDGs), and higher education qualifications, were found to be statistically significant factors influencing farmers’ intentions to adopt sheep scab control measures. This study provides a solid foundation for how to promote behavioural changes among sheep farmers to improve their ability to implement effective disease control measures, helping to tackle this challenging disease in a more sustainable way in the future.