This paper explores the design principles underlying AI-powered conversational support systems aimed at fostering student thriving in educational environments. As artificial intelligence increasingly integrates into learning ecosystems, chatbots and virtual assistants are emerging as accessible tools to promote engagement, motivation, and personalized guidance. Drawing on interdisciplinary literature from educational psychology, human-computer interaction, and learning sciences, this study identifies key principles for designing effective AI conversational agents, including empathy simulation, adaptive feedback, goal-oriented dialogue, and transparency in AI behavior. Case examples illustrate how these principles can be operationalized to support academic persistence, emotional well-being, and skill development. The paper concludes with recommendations for future research and implementation strategies to ensure AI tools align with diverse student needs and promote inclusive, ethical learning experiences.