PurposeCOVID-19’s attack on the system of education left the learning of many students in limbo. For minimizing this effect, the current study sought to probe how Mobile-Assisted Language Learning (MALL) can facilitate English as a Foreign Language (EFL) learners’ vocabulary knowledge. In so doing, a quasi-experimental pretest-posttest research design was adopted to check the effect of a newly developed application (i.e. visual vocabulary learning, hereafter VVL) in an EFL classroom.Design/methodology/approachTo complying with the objective, a number of intermediate students (N = 40) were considered to participate in the study. They were assigned into a visual learning group (VLG) and a nonvisual learning group (NVLG) comprising 20 students in each. The VLG was directed to learn vocabulary by a VVL, and the NVG, a conventional method was employed for vocabulary instruction. An independent samples t-test was run to screen the efficacy of the intervention.FindingsThe finding revealed that participants in the VLG outperformed significantly in the posttest. The finding is beneficial for EFL teachers, syllabus designers, and material developers to take advantage of mobile applications in teaching vocabulary.Originality/valueThis study was conducted during COVID 19 between two groups in Iran.