This study investigated the Effect of Collaborative Instructional Strategy on Academic Achievement of Senior Secondary Students in Biology in Otukpo Local Government Area of Benue State, Nigeria. The study has two research objectives, two research questions were raised and answered, and two hypotheses were tested at a 0.05 level of Significance. A quasi-experimental design was adopted. Biology Achievement Test (BAT) instruments were developed and administered to 425 samples from the population of 1484 Senior Secondary School (SSI) students in Otukpo Local Government Area, Benue State. A purposive sampling technique was used in the selection of the samples. Biology Achievement Test (BAT) was validated by three experts. The reliability of the BAT was 0.95 using the Kuder-Richardson formula (K-R20) The experimental group was taught using the Collaborative instructional strategy while the control group was taught using the conventional Teaching method. Research questions were answered using mean and standard deviation, while hypotheses were tested at 0.05 level of significance using ANCOVA. Results revealed significant differences in achievement of students taught using the Collaborative instructional strategy and their counterparts taught using the traditional Teaching method. The study further revealed no statistically significant differences in the achievement of male and female students exposed to the Collaborative instructional strategy. Based on the findings, the study concluded that the Collaborative instructional strategy is effective and gender friendly and it was recommended for adoption in the teaching and learning of sciences, particularly Biology.