Attitude has been considered to play a major role in second language learning. Learners’ tendencies to like or dislike a subject affected their overall performance. The study examined the relationship that existed between students’ attitudes and Kiswahili language performance as well as the relationship between gender and attitude towards Kiswahili. The study employed a cross-sectional survey design. A simple random sampling procedure was used to select 45 schools, 343 students and 121 teachers of Kiswahili. The research instruments included questionnaires for teachers, an attitude scale for students, and document analysis guide and the Kiswahili achievement test. The test re-test method was used to ascertain the reliability of the instrument’s results. Descriptive data were analysed by use of means, standard deviations, and percentages, while inferential data were analysed by use of t-test for significance of r and Independent Sample T-tests. The study findings established that there was a significant relationship between student attitude and Kiswahili subject performance. Students with positive attitudes performed better than those who held negative attitudes towards the subject. Regarding gender and attitude, it was evident that the Female students exhibited a positive attitude towards Kiswahili as compared to their male counterparts. Additionally, female students performed better in the Kiswahili subject, but the difference was non-significant. The study recommended that teachers needed to come up with teaching methods that would foster positive attitudes among students, like engaging students in co-curricular activities, symposiums, debates, and dramatising set-books, among others.