The idea of Competency-Based Curriculum (CBC), which was anchored majorly on mastery of particular skills started to be implemented and accepted in educational institutions in Kenya. This reform benefited from the contribution that parents made to schools which played a vital role in the success of the reform. The purpose of this study was to find out how parents supported the students in the public primary schools to embrace the CBC approach. The study was guided by three key objectives: to justify the involvement of parents in school-based activities for successful CBC implementation, to quantify the parents’ involvement in home based activities and to analyze the role of communication between parents and teachers for successful CBC. The target population was 18 public primary schools, head teachers of the 18 schools, 100 teachers and 600 parents. Teachers were purposively selected using stratified random sampling and the parents were randomly sampled. Sources of data included questionnaires and interview schedules. The instruments used in the study were validated in a pilot study conducted in Lugari Sub-County and the test-retest method assisted in establishing the reliability. Stratified Random Sampling was used to select the teachers involved in the study. Parental involvement and communication between parents and teachers were found to be the quintessential in the success of the CBC. There was an increase in newsletters, meetings, and a structured use of technology and social media that enhanced parental involvement. Teachers reported that greater levels of engagement produced better educational relationships which ameliorate student achievement. The conclusions of the study were that with the increase of parental participation there would be enhanced implementation of CBC. Children active parents helped in enhancing students’ performance, attendance, and emotional wellbeing. Among the recommendations of the research were the following: schools should extend the range of activities that may interest parents and fit into their timetable, improve methods of communicating with parents, and organize workshops to teach parents what they need to know and how to help their children in school.