In today’s highly competitive, volatile and intense service environment, marketers are seeking ways to connect and engage with their customers in order to build longstanding relationships and achieve customer loyalty. However, achieving loyalty in itself is not sufficient, as research has established that even loyal satisfied customers can still defect to the competition. Thus, ascertaining the key determinants, which make customers want to switch between service providers, is particularly important to service providers. Having such knowledge will enable service providers to prioritise on customer retention initiatives with business strategies that aim to increase profitability, by mitigating the effects of these churn factors. This study sought to identify key factors that determine customer churn in Zimbabwe’s mobile telecommunications sector. Drawing from the push-pull mooring theory, this study investigated the influence of customer dissatisfaction, low switching cost, lack of customer support, lack of sufficient or adequate advertising, as well as increased security/ethical concerns of customers. A quantitative research method was adopted, with data collected from a sample of 413 Zimbabwean mobile subscribers, using structured questionnaires. Multiple linear regression analysis was applied to analyse the causal effect of the factors hypothesised as predicting customer churn. Factor analysis, validity and reliability tests were performed to confirm the reliability and validity of scales. The results reveal that key determinants of customer churn are customer dissatisfaction and poor complaints management system in place. Accordingly, mobile service providers are encouraged to prioritise initiatives that enhance customer satisfaction as well as investing in systems and methods that effectively and satisfactorily resolve customer complaints, thereby ensuring customer retention.