This study delves into the intricate relationship between pre-service teachers' (PSTs') Mathematical Knowledge for Teaching Fractions (MKTF) and its influence on their teaching practices. Grounded in the premise that MKTF domains exhibit interconnectivity, shaping the constructs of teaching practices, the study employed the mathematical task framework and the framework for mathematical knowledge for teaching. Utilizing the Mathematical Knowledge for Teaching Fractions test and the Teaching Practices test, data were collected from 171 PSTs. Regression analyses uncovered significant effects of MKTF domains on five teaching practice components, underscoring the pivotal role of a teacher's mathematical knowledge in effective teaching. Notably, among the six MKTF domains, the KCFS domain emerged as the most fundamental, strongly predicting various MKTF domains and influencing teaching practice constructs. This study underscores the significance of the KCFS domain in shaping both MKTF domains and instructional practices. The findings bear implications for the education of PSTs in Ghana and other nations facing similar educational landscapes.