Abstract: Constructive feedback is an essential part of mentoring newly recruited teachers. The purpose of this research was to examine the effect of constructive feedback on the quality of teaching and learning practice of new teachers in international primary schools in Nairobi City County. The study was grounded on Katz developmental stage theory. The research design employed in this study was a mixed methods convergent design, specifically parallel-databases variant. Quantitative method utilised a cross-sectional design while qualitative adopted a phenomenological design. Target population consisted of all 25 schools, 25 headteachers, 25 mentors and 118 new teachers. Stratified proportional sampling was employed to sample 8 schools, 8 headteachers automatically included, while 8 mentors chosen using purposive criterion sampling. Krejcie and Morgan table was used to determine the sample size for selecting 92 new teachers, utilising cluster sampling. From the analysis, most of the respondents (39, 49.4%) conceded that constructive feedback was extremely important to the mentoring program. The study revealed that a strong positive and significant relationship exists between constructive feedback and the quality of teaching and learning practice (correlation coefficient 0.729**). This implies that constructive feedback has a strong positive association to the quality of teaching and learning in international primary schools in Nairobi City County. The study findings also indicated that constructive feedback offers new teachers an opportunity to reflect on their teaching methods, identify areas for improvement, and make informed adjustments to their instructional strategies. The study recommended that policymakers should prioritize the establishment of robust mentoring policies tailored to the unique needs of new teachers in international primary schools. Headteachers should prioritise training mentors on modern global trends in mentoring and provide cross-cultural competency training to address the diverse needs of international teachers and students. These programs should pair new teachers with experienced mentors who can provide constructive feedback, share best practices, and offer guidance on navigating the complexities of teaching in diverse cultural contexts 

Keywords: Constructive feedback, quality of teaching and learning, cultural contexts, instructional strategies, comprehensive mentoring programs