This study examined the relationships between motivational processes and mental toughness in college skiers based on the self-determination theory (SDT). A total of 332 participants from four skiing items completed four psychological scales assessing motivational factors and mental toughness. The findings revealed that a task-involving climate is positively associated with basic psychological needs, eliciting a positive pathway to autonomous motivation and controlled motivation, thereby positively affecting mental toughness. In contrast, an ego-involving climate is negatively associated with basic psychological needs, eliciting a negative pathway to amotivation, thus negatively affecting mental toughness. The findings highlight the complex interplay between a series of motivational factors and athletes’ mental toughness, underscoring the need to integrate mental-toughness-related factors into the motivational framework.