A review of empirical studies on teacher motivation indicates decreasing levels of motivation among secondary school teachers ultimately leading to minimal achievements of the projected Kenya’s Vision 2030. This study examined the school curriculum as a determinant of secondary school teacher motivation in Kenya in curriculum implementation. The research adopted a survey study design, adopting mixed methods research approach with an aim of fortifying and converging both quantitative and qualitative data. The respondents were sampled from 46 secondary schools located in Nyeri and Kirinyaga counties of Kenya. The findings of this study inform curriculum planners, education leadership and policy makers on the school curriculum as a core determinant of teacher motivation in secondary schools that influence curriculum implementation in Kenya.