The use of mobile technology at secondary education level may be one of the effective strategies to meet the needs of today's students who want to learn a foreign language. Foreign language learners should learn idioms of a language as well as its words and grammatical structures. In this sense, concept cartoons can be thought of as an effective tool that can be used to embody abstract concepts for teaching idioms. This study aims to investigate the effect of delivering concept cartoons in different learning environments on learning English idioms. To this end, a blended learning environment with a learning management system was developed for 7th grade students. The effect of concept cartoons on academic acheievement and retention levels of English language idioms was determined when concept cartoons were delivered through Whatsapp application in mobile environment in the experimental group and presented in face-to-face learning environment in the control group. In this research, a sequential explanatory mixed method model was used. The quantitative data of the study were collected via an achievement test used as a pretest, posttest, and retention test while a focus grup interview was conducted for qualitative data. The findings indicate that delivery of concept cartoons to students through mobile learning and in face to face learning environments did not create a significant difference in participants‘ academic achievement and retention levels. Nonetheless, the students‘ experiences regarding concept cartoons and mobile learning environment were found positive. Research findings contribute to the media or method discussion.