Good health and the promotion of well-being for all is the third of the 17 Global Goals included in the 2030 Agenda for Sustainable Development. Contributing to this goal, the current study aimed to examine the relationships between one kind of athlete well-being, namely state organic self-talk, and personality traits and the basic psychological need satisfaction and frustration within their sport. Athletes (n = 691; mean age 21.65) from a variety of individual (n = 270) and team sports (n = 421) completed a multi-section questionnaire capturing the targeted variables. Three-step hierarchical regression analyses revealed the following: In step 1, all personality traits were to some extent a significant predictor of athletes’ organic, spontaneous self-talk dimensions and goal-directed self-talk functions. In step 2, need satisfaction significantly contributed to all spontaneous self-talk dimensions and goal-directed self-talk functions (except for creating functional deactivated states) over and above personality. Finally, in step 3, need frustration significantly contributed to negative spontaneous self-talk dimensions and to all goal-directed self-talk functions (except for instruction) over and above personality and need satisfaction. Overall, our results indicate the importance of personality traits as personal antecedents, and perceptions of basic psychological need satisfaction and frustration as social–environmental antecedents in shaping athletes’ state organic self-talk.