The study aimed at investigating the effects of using animations in teaching Kiswahili reading comprehension on students achievement among secondary school students' in Njoro Sub-County Kenya. Solomon Four Non-Equivalent control group design was used in the study. Target Population comprised all 14,292 students in the public co-educational secondary schools in Njoro Sub County. The accessible population included the 4,745 Form Two students from public co-educational secondary schools in the Sub-county. Purposive sampling technique was used to select one form two class from each of the four co-educational secondary schools which provided the sample size for the study 160 students. The four schools were randomly assigned to experimental and control groups. For the experimental group, animations were used during the lessons while conventional methods were used for the control groups. Data was collected using Kiswahili Reading comprehension achievement test, whose reliability coefficient of 0.76 was attained using Kuder -Richardson 20 (KR-20). The null hypothesis was tested at 0.05 level of significance. Data was analysed using t-test, ANOVA and ANCOVA. Before the treatment, a pretest was administered then after four weeks a post-test. The findings proved that after the treatment, the students in the experimental groups attained higher scores compared to the ones in the control groups. This signifies that the use of animations in teaching had an effect on students' achievement in Kiswahili reading comprehension. Therefore, teachers are encouraged to incorporate the use of animations in teaching Kiswahili reading comprehension in attempt to improve achievement in Kiswahili subject.