The purpose of this study was to investigate the effects of Augmented Reality (AR) technology on vocabulary development and attitudes toward AR in pre-school English instruction. The study, which was grounded on a pretest-posttest control group quasi-experimental design, included 36 pre-school children aged from 4 to 5. While the participants in the control group used flashcards, matching cards, and puzzles to learn English equivalents of target vocabulary, the participants in the experimental group used the same materials presented through AR applications, enabling them to see 3D animated models and listen to English pronunciation. The results revealed significant differences between groups in terms of vocabulary learning, attitude, and enjoyment levels, with the experimental group performing better. Although there was no statistically significant difference in terms of emotions between the groups, the participants in the experimental group developed more positive feelings towards AR-supported activities than those in the control group. In addition, some participants with lower emotional levels in the control group had undecided and unhappy emotional states. As a result, it can be said that AR technology contributed to language learning in pre-school English classes and that this technology positively influenced the participants' attitudes and enjoyment.