Numerous researchers in education recognize that vocabulary is essential in foreign language learning. However, students often encounter vocabulary that is difficult to remember. Providing effective vocabulary learning strategies is therefore more valuable than teaching students a large amount of vocabulary. The purpose of this study was to encourage teachers to apply these strategies by using mobile phones and technology to facilitate vocabulary learning. Participants were divided into learner-constructed concept-mapping and text-only strategy groups. The concept-mapping group received the vocabulary instruction according to the concept maps constructed by the students themselves while the other group received the vocabulary in a random order. The research question was as follows: Does mobile English vocabulary learning based on concept-mapping strategy have a significant effect on EFL learners' vocabulary performance? For vocabulary learning acquisition and retention, the concept-mapping group performed significantly superior to the text-only group.