Strategic planning is important for strategic management of organization as the success of the organization is dependent on external environment and how it aligns its resources internally to exploit opportunities and cover its weaknesses. The study aimed to investigate the effects of strategic planning on organizational performance. The main objective was to specifically establish the effects of strategic planning on strategic implementation, evaluation, work environment and management participation. The study was guided by Resource based view theory and Dynamic capability view theory. The scope of the study was limited to the Ministry of Foreign Affairs and focused on 284 staff members at the Ministry Headquarters in Nairobi, Kenya. The study utilized a descriptive research design. The design gave an opportunity for a comprehensive description and analysis of the variables involved in the study while clearly outlining the relationship between variables. A stratified sampling technique was used in this study. The sample was determined through Krejcie and Morgan’s method. It was effective as the stratified method made sure that the sample size of each level, which was represented in various departments is proportional to the population size of the Ministry. The questionnaire was administered to selected sampled employees in upper middle management to senior management. Questionnaire was used as the main instrument of data collection which underwent pilot study to test the reliability and validity of the research instrument. The content validity was used in the study which was determined by content validity index. The study used Cronbach’s alpha formula to test reliability, with value of 0.7. Descriptive statistics was used for data analysis.