Despite the fact that Chemistry is the gatekeeper and foundation of all other science subjects, overall performance in Chemistry among secondary school students in the country remains poor. This study, therefore, sought to find out the Effects of Laboratory Exposure on Students’ Academic Performance in Chemistry Practical in Public Secondary Schoolsin Lang’ata Sub-County. The objectives of the study were; to find out the availability of chemistry laboratory facilities, to examine the availability and use of chemistry laboratory resources; to establish the frequency of use of chemistry laboratory and to determine the personal practical skills of teachers/ lab technicians and their effects on students’ academic performance. The study was guided by John Dewey’s Constructivist Learning theory. The researcher used the descriptive survey design and questionnaires as the research instruments for both students and teachers to collect data.The sample size was 142 comprising 132 students of forms II and III selected randomly from 3 public secondary schools (Boy’s, Girl’s and Mixed)and Purposive sampling was used to sample 10 teachers/lab technicians of the 3 schools.Statistical package for social sciences (SPSS version 28.0.1.1) was used to facilitate data analysis. Findings of the study established that 51.3% of secondary schools in Lang’ata Sub-County have enough basic laboratory learning facilities necessary for better learning and improved achievement in the national examination in chemistry practical (Chemistry Paper 3). However, 77.9% of the teachers confirmed that availability of laboratory facilities have an effect on the performance of students.Consequently, it was realized that most Chemistry teachersused the resources available in the Chemistry laboratory during class experiments. The study revealed that there is a positive relationship between using Chemistry laboratory and students’ academic performance in Chemistry practical as indicated by 88.9% of the teachers. In conclusion, students whose teachers always take them to the laboratory during practical lessons performed better in practical examinations. Subsequently, this study proposed that there is need as a matter of policy to ensure that all students who take Chemistry at KCSE level are exposed to an adequate level of laboratory utilization, access of chemistry practical session and sufficient frequency of chemistry practical in order to promote good performance in chemistry practical. The study recommends that teachers should be creative and innovative in the use of laboratory equipment in conducting experiments and students should develop positive attitudes towards the teaching and learning of chemistry especially for chemistry practicals.