While recent years have witnessed increasing attention to technology-enhanced language learning, investigation regarding how technologies facilitate digital storytelling outcomes among middle school students in English-as-a-foreign-language contexts remains insufficiently explored. Studies concerning the effects of different presentation modes such as anthropomorphized robots versus PowerPoint on digital storytelling outcomes have been insufficient, and specific probes into affective domains such as emotion, grit, and perceptions have been even scarcer. The interplay between these issues, therefore, has yet to be validated. This mixed-methods study, accordingly, addresses these concerns by examining not only the relationship among digital storytelling outcomes, emotions, and grit in different presentation modes (Robot vs. PowerPoint), but also student perceptions. Focusing on 52 ninth-grade middle school students from a middle school in central Taiwan, the results from diverse data sources (pre-/post-tests, an questionnaire about emotions, a grit survey, a perception survey, and reflective journals) identified the benefits of both presentation modes. Nonetheless, the robot-assisted mode was more advantageous in making the learners grittier and led to higher storytelling outcomes as well as more positive affect. Storytelling outcomes were strongly and positively correlated with grit, including perseverance of effort and consistency in interests. Nonetheless, perseverance of effort was the best predictor of storytelling outcomes in the experimental group, suggesting higher perseverance of effort for better storytelling outcomes. In terms of student perceptions, the robot-assisted group using Kebbi Air was more positive about the overall learning experience, as demonstrated by higher responses to motivation, effectiveness, engagement, and satisfaction.