This explanatory sequential mixed-method study aimed to investigate the mind maps (virtual/non-virtual) effect on the development of EFL learners’ ability to apply their knowledge of grammar and structure of the language in a natural way. The study also examined the issue of EFL lower-intermediate students’ achievement for learning grammatical structures throughout their studies. To this end, a group of 90 out of 112 Iranian EFL students at lower-intermediate level of general language proficiency were selected and randomly assigned to three groups based on the results of the KET. In this study, three groups of students participated. Two of the groups were experimental, and one was a control group. Before starting the treatment, all groups took a grammar test and a motivation questionnaire. The first experimental group received instruction using virtual mind maps, while the second experimental group used non-virtual mind maps. The control group received traditional instruction without any special treatment. After the treatment, all groups took the motivation questionnaire and grammar test again. The t-test analyses confirmed that both virtual and non-virtual mind maps had a significant impact on Iranian EFL students' achievement of grammatical structures to learn them. However, when comparing the two experimental groups (virtual and non-virtual mind map groups), the study found that virtual mind maps had a more significant effect on participants' grammatical knowledge. Additionally, a semi-structured interview revealed that most participants had a positive opinion about using virtual mind mapping in EFL classrooms for teaching English grammar. The pedagogical implications will be discussed.