Although gamification is one of the latest education trends, it has not been investigated adequately in the Egyptian EFL context. Hence, this mixed-method study aimed to explore the effect of using gamification on Egyptian EFL learners' vocabulary knowledge and their attitudes toward gamification use. The study followed a pre-posttest quasi-experimental research design. A total of 68 English Majors in the Faculty of Education at New Valley University participated in this study. The instruments included a vocabulary test (APTIS), an attitude questionnaire (designed by the researcher), learning logs and follow-up interviews. The experimental group used Quizizz, whereas the control group used paper-based sheets. After a seven-week treatment period, the participants were post-tested. The results showed significantly increased vocabulary knowledge of the experimental group in the APTIS test compared to the control group. The effect size of the treatment was remarkable (Cohen's d = 1.8). The questionnaire and interview data indicated positive attitudes toward the use of gamification in learning vocabulary. The interviewees found gamification more exciting and enjoyable than traditional learning methods. However, they experienced some challenges in internet access. In this study, gamification was deemed effective in enhancing EFL learners' vocabulary knowledge. Gamification efficiency may be due to its challenging and motivating nature in adding inspiring gaming elements to traditional learning. This study recommends the use of gamification as a useful and motivating tool for enhancing lexicon competence.