The research aimed at enhancing EFL grammatical competence among first year secondary school students through using gamification- based strategy. It adopted the quasi-experimental design. The participants of the study were 60 first year secondary stage students enrolled in Sidi Salem Secondary School for Girls, Kafr El-Sheikh Governorate. The participants were divided into two groups, one control group (taught using the traditional method) and another experimental group (taught using gamification-based strategy). The two groups received pre- and post- administration of the study instruments. To fulfill the purpose of the study, the following instruments were designed and used by the researcher: An EFL Grammatical competence checklist required for first year secondary school students; A pre/ post grammatical competence test to measure students' grammatical competence. The experimental treatment was conducted during the first semester in the academic year 2020/2021. Results revealed that gamification- based strategy was effective in developing EFL secondary stage students' grammatical competence. This can be assured by these points: (a)The experimental group students outperformed the control group students in the post administration of the grammatical competence test, (b)The experimental group students' mean score in the post -administration of the grammatical competence test were much better than their mean score in the pre- administration.