The study investigated the effect of metacognitive learning strategies on academic performance in English language among students in public secondary schools in Kenya. The study adopted Solomon four-group experimental design. The participants comprised 283 Grade 11 students from four public secondary schools. The study utilised a modified standardised metacognitive learning strategy questionnaire (MLSQ) to measure the use of metacognitive learning strategies by students in English language. Cronbach's alpha ([alpha]) was computed to investigate the internal consistency of the questionnaire and the overall reliability coefficient of [alpha] = 0.827 was reported. The findings is that there is significant difference between experimental group posttest scores (Group-3) and control group posttest scores (Group-4), t(53) = -8.095 (p < 0.05). The conclusion is that metacognitive learning strategies are effective in enhancing student's academic performance in English language. Teachers of English language should therefore utilise metacognitive learning strategy during instruction in schools.