The purpose of the study was to examine the relationship between Contextual factors and the implementation of the new O-level curriculum in selected secondary schools in Kampala District, Uganda. The study was guided by three objectives that‟s; to find out the relationship between school environment and the implementation of the new O-level curriculum in selected schools in Kampala District; to find out the relationship between Teacher competence and the implementation of the new O-level curriculum in selected secondary schools in Kampala District and lastly to find out the relationship between student‟s competence and the implementation of the new O-level curriculum in selected secondary schools in Kampala district, Uganda. The study adopted a correlational research design that involved 88 secondary schools out of the 113 targeted secondary schools in Kampala making a response rate of 77.9 percent. The study employed both quantitative and qualitative tools and the quantitative tool had a validity and reliability of 0.821 and 0.949 respectively. SPSS version 23, was used for analysis on descriptive analysis, Pearson correlation to test relationship between variables and the regression to determine the correlation between the study variables. Meanwhile qualitative data was subjected to a thematic analysis technique. It was found that school environment had a moderate positive association on the implementation of new O-level curriculum, teacher‟s competence had a strong positive association on implementation of the new O-level curriculum and finally student‟s competence had a strong positive association on implementation of the new O-level curriculum. All the three independent variables accounted for 54.0% of the changes in the dependent variable. The study recommended that there should be Curriculum Training and Professional Development, Supportive School Leadership, Curriculum Alignment and Resources, Peer Learning and Collaboration. The study highlights areas for further studies like Investigating the impact of school infrastructure, such as classroom conditions, availability of technology, and the quality of teaching materials, on curriculum implementation and student performance. Examining the effectiveness of teacher professional development in enhancing the comptencies of teachers to attain positive curriculum implementation and researching on the corrlation between motivation, job satisfaction and their ability to effectively implement the new O-level curriculum. Identify factors that contribute to teacher motivation and satisfaction. The study had several limitations. First, sampling bias was present as the selection of schools in Kampala did not represent schools in the region. The study's timeframe was limited, hindering the capture of long-term trends of the new O-level curriculum implementation.