This study examined the relationship between teachers’ behavioural practices and character development among pupils in private primary schools in the Federal Capital Territory (FCT), Abuja. The study specifically investigated how teachers’ modelling behaviour and reinforcement practices contribute to pupils’ character development outcomes. A descriptive survey research design was adopted for the study. The population comprised 48,750 teachers and head teachers across registered private primary schools within the six Area Councils of the FCT. A sample size of 381 respondents was selected using Krejcie and Morgan’s sample size determination table. Data were collected using a structured questionnaire titled Teachers’ Behavioural Practices and Character Development Questionnaire (TBPCDQ). The instrument was validated by experts in Educational Management and Measurement and Evaluation, while reliability was established using the test-retest method, yielding a reliability coefficient of 0.78. Data collected were analysed using mean, standard deviation, and Pearson Product Moment Correlation at a 0.05 level of significance. Findings revealed that teachers’ modelling behaviour and reinforcement practices significantly relate to character development among pupils in private schools in the FCT, Abuja. The study further established that positive teacher behaviours such as punctuality, honesty, fairness, empathy, consistency, and respectful communication significantly contribute to the development of desirable character traits among pupils. The study concluded that teachers’ behavioural practices constitute an important component of school-based character development processes. It was recommended among others that private school proprietors should institutionalise teacher behavioural standards, integrate character-based indicators into teacher performance evaluation systems, and provide continuous professional development programmes focused on behavioural modelling and positive reinforcement practices.