Globally, lives of seven billion people lie in the hands of 59 million health workers for care throughout their lifespan. This study purposed to establish the influence of cognitive learning objective domain on clinical competence development among clinical officer interns in Meru and Tharaka-Nithi Counties. The study used a descriptive longitudinal research design, which was necessitated by need for follow-up of respondents. The study had two groups as respondents made of clinical supervisors and clinical officer interns. The study used non-probability sampling method of purposeful for supervisors and probability sampling method of stratification for clinical officer interns. The study targeted 60 supervisors and selected purposefully a sample of 30, plus 150 Clinical officers interns and selected a sample of 109 using formulae by; Glen Israel, (2009). The study employed a semi - structured interview guide instrument on clinical supervisors and a structured questioner instrument on clinical officer interns. The findings of the study indicate that internship improved clinical competence development clinical officer Interns, as evidenced by lower scores before than after internship. Findings suggest that competencies of clinical officer interns are not yet well-developed as they start their internship, but improved at the end of internship. Significant difference was attained during their training on knowledge and skills but not much on attitudes. The study recommends that internship must be emphasized for improvement of cognitive and psychomotor with mentorship program for effective domain competence development among clinical officer interns in Kenya.