This study investigated the effect of learning cycle constructivist-based approach on secondary schools students' academic achievement and their attitude towards chemistry. The design used was a pre-test, post-test non randomized control group quasi experimental research design. The design consisted of two instructional groups (learning cycle group and lecture group), two attitudes (positive and negative) and repeated testing (pre-test and post-test). The samples of the study comprised 120 students from four mixed senior secondary school class II (SS II) randomly drawn from the population. The instruments used in collecting data were chemistry achievement test (CAT) and chemistry attitude scale (CAS). The data were analyzed using mean, standard deviation and analysis of covariance (ANCOVA) used to compare the positive and negative attitude with the experimental group on academic achievement. The findings of the study indicated that learning cycle had a significant effect on students' achievement in chemistry, students taught with learning cycle significantly achieved better in chemistry Post-test than those taught with lecture method, and a non-significant difference existed in academic achievement between students with positive and negative attitude after treatment. It was concluded that learning cycle method seems an appropriate instructional model that could be used to solve the problems of science teaching and learning since it enhances students' achievement, facilitates learning and its effectiveness is not limited by attitude.