<p>This study examined the effect of using Gamified Metacognitive Worksheets on improving literacy and metacognitive abilities of ninth-grade students in learning about environmental change. The study represented the implementation and evaluation phase of previously developed metacognition and gamification integrated student worksheets. A quasi-experimental design using a non-equivalent pretest–posttest control group was employed. The population consisted of three junior high schools, with samples drawn from two ninth-grade classes in each school, totaling 204 students. The research instruments included metacognition- and gamification-based student worksheets and a 60-item multiple-choice test designed to measure literacy (scientific, environmental, and numeracy literacy) and metacognition (designing analogies, organizing word arrangement and evaluating word guessing). Data were analyzed using descriptive statistics and Multivariate Analysis of Covariance (MANCOVA). Students’ competencies, as analyzed based on indicator levels, ranged from low to very high in literacy and from low to high in metacognitive aspects. The results showed that students’ literacy scores increased from a mean of 66.40 (moderate) to 79.55 (high), while metacognitive scores improved from 54.19 (low) to 67.98 (moderate). MANCOVA results indicated that the implementation of Gamified Metacognitive Worksheets was associated with statistically significant differences on students’ literacy and metacognitive abilities (<i>p</i> &lt; 0.05), with a large effect size (ηp² = 0.349). Thus, there was a significant difference in students’ ability profiles between the experimental and control groups after controlling for covariates. The metacognitive and gamification integrated worksheets were associated with improvements in students’ literacy and metacognitive abilities, indicating higher levels of scientific literacy and metacognitive performance.</p>