This study explored the factors that affect the adaptation and usage of Artificial Intelligence (AI) among secondary school teachers in Mbeya City Council, Tanzania. A descriptive quantitative research design was used, involving a population of 1,336 teachers, from which 320 were selected through stratified random sampling. Data were collected using structured questionnaires and analyzed using the Statistical Package for the Social Sciences (SPSS) version 26. Descriptive statistics such as frequencies and percentages were used to summarize data, while multiple regression analysis was applied to examine the relationship between perceived usefulness, perceived ease of use, facilitating conditions, social influence, and AI adoption. The results showed that both perceived usefulness and perceived ease of use had a negative but significant influence on AI usage, while facilitating conditions and social influence had weak or insignificant effects. The study concludes that low AI usage among teachers is mainly caused by inadequate training, poor infrastructure, and limited institutional support. It recommends improved teacher training, better digital infrastructure, and stronger policy implementation to promote effective AI use in secondary schools..