The recent growth in snack food types has led to increasing demand for attractive snack food packaging. To attract consumers’ attention successfully, it is essential to influence their decisions by meeting their packaging needs. This study examines the interrelationship between different packaging design characteristics and their influence on consumers’ purchase decisions. Twenty-five design professionals and 121 students participated in the study. A survey developed for applying the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method was used to evaluate the importance of design characteristics. The results showed that color, shape, image, line, and typography were the five most essential design characteristics influencing consumer purchase behavior, and that image is the most significant impact factor on consumer purchase decisions. Surprisingly, materials and technology have little influence on consumers’ decisions. Therefore, enhancing these packaging design characteristics can improve the interaction between snack food packaging and consumers and increase food sales.