© 2021, Bastas. All rights reserved.Previous research claimed that integration of augmented reality on educational settings helps to improve academic achievement of students in collaborative learning environments, as well as to improve their retention and ability to translate this within other environments. Since augmented reality is still considered relatively novel technology in educational fields, there is an inherent need for research-based guides to design effective and feasible augmented reality tools for school-based learning. The main aim of this study was therefore to design and develop an augmented reality learning toolkit to foster spatial ability in middle school students using mobile devices. The study was conducted in two parts, as preliminary research and a prototyping phase. The findings guided the characteristics for designing an augmented reality learning toolkit with a set of spatial tasks aimed at middle school students. In light of the results, it can be inferred that the students were able to use this designed toolkit to perform their spatial ability through given spatial tasks since the students encountered no technical difficulties with the final toolkit prototype, and that they were able to use the toolkit assuredly. In conclusion, the study showed that augmented reality seemed helpful in enhancing the usage of mobile devices, not just for the reading of books, communication or playing games, but also as a support mechanism for the learning of mathematics. Thus, the augmented reality toolkit developed in this study presents a new way for students and/or teachers to use mobile devices in the learning and teaching of mathematics.