Secondary school Geography students continue to experience difficulties in developing spatial reasoning and environmental awareness, skills that are central to understanding complex geographical phenomena. These challenges are often associated with conventional, lecture dominated instructional practices that limit active cognitive engagement. Anchored in the Cognitive Theory of Multimedia Learning and constructivist learning principles, this study investigated the effect of gamified instructional videos on spatial reasoning and environmental awareness among Senior Secondary School II Geography students in Katsina State, Nigeria. A quasi-experimental pretest, post-test control group design was employed. Using a multistage sampling technique, 148 students were drawn from public secondary schools and assigned to experimental and control groups using intact classes. Data were collected using validated instruments measuring spatial reasoning, environmental awareness, and Geography achievement. The experimental group received instruction on climate zone concepts through gamified instructional videos, while the control group was taught using the conventional lecture method. Data were analyzed using descriptive statistics, independent samples t-test, and Analysis of Covariance (ANCOVA)at the 0.05 level of significance. Results revealed that students exposed to gamified instructional videos demonstrated significantly higher spatial reasoning skills and environmental awareness than those taught conventionally. The findings highlight the instructional value of gamified multimedia in fostering deeper cognitive processing and meaningful engagement with environmental concepts in Geography education.