This study investigated the effects of metacognitive and self-efficacy teaching strategies on senior secondary school biology students’ academic achievement in Adamawa State, Nigeria. Three research questions andseven null seven hypotheses guided the study. The study adopted the pre-test, post-test, non- equivalent control group, Quasi-experimental research design involving a 3x2x1 factorial matrix. The population was 24,960 SS II Biology students. The sample of the study was 184 students (85 males and 99 females) drawn from three schools. Two instruments were used for data collection namely the Biology Achievement Test (BAT) and Student Self-Efficacy Questionnaire (SSEQ). Kuder-Richardson formula (KR-21) and Cronbach Alpha method were used to determine the reliability efficient of BAT and SSEQ. The reliability coefficient of 0.81 and 0.78 were obtained for BAT and respectively SSEQ. The Research questions were answered using Mean and Standard deviation. Analysis of Covariance (ANCOVA) was used to test the null hypotheses at 0.05 level of significance. The findings of the study showed that there was significant difference between metacognitive strategy and lecture method on biology students’ academic achievement in favour of metacognitive strategy (0.001). There was no significant difference between male and female students taught biology with metacognitive strategy and lecture method (0.061). There is significant difference between high self-efficacy and low self-efficacy students taught biology with metacognitive strategy and lecture method in favour of high self-efficacy students (0.019). There is no significant interaction effect of treatment and self-efficacy on students’ achievement in biology (0.079). There is no significant interaction effect of treatment and gender on students’ achievement in biology (0.200). There is no significant interaction effect of self-efficacy and gender on students’ achievement in biology (0.965). There is no significant interaction effect of treatment, self-efficacy and gender on students’ achievement in biology (0.924). It was recommended among othersthat there is need to empower students’ metacognitive skills in order to improve their academic abilities. Metacognitive teaching strategies should be developed in biology teachers to improve metacognitive attitudes and knowledge as well as skills.