Over the years, gamification has played an important role in English education. Despite the promising results, there is a scarcity of research on gamified English teaching. Additionally, most studies addressing this topic used tools with problematic validity, posing challenges in interpreting their findings. Therefore, the objectives were to develop and validate a measure assessing the teacher-perceived applicability of gamification applications and the perceived effect on learners' motivation and learning outcomes. Two samples of 278 (M = 41.2, SD = 9.38; 81.3% females) and 333 (M = 43.7, SD = 9.2; 87% females) participants were used for Exploratory and Confirmatory Factor Analyses, respectively. Network analysis examined the mutual dynamics between the items. Additionally, two retest samples were collected to explore the stability of the scale. Measurement invariance was examined between the samples and education levels. The construct validity was assessed by examining associations with other constructs using Spearman's Rank correlations. The results supported the four-factor model (CFI = 0.863; TLI = 0.85; RMSEA = 0.076; SRMR = 0.077) with excellent internal consistency (Cronbach's [alpha] = 0.91 and McDonald's [omega] = 0.94) and excellent stability (ICC = 0.96). The network analysis identified 9 communities. The measurement invariance revealed that the scale measures the same across different education levels and samples. Spearman's Rank correlations suggested statistically significant associations between individual subscales and selected constructs except between learning outcomes and general point averages. Altogether, the scale exhibits a high temporal and cross-level robustness, making it a valuable tool for gamification assessment in English teaching.