Preschool toys are discarded well before their technical lifespan, exacerbating plastic waste and undermining circular-economy ambitions. Addressing behavioural—rather than purely material—drivers of discard, this research explores how caregiver-defined sustainability priorities can be integrated with temperament-aligned design guidance to extend toy use. Four studies frame the inquiry: (1) an Analytic Hierarchy Process with 220 caregivers shows that educational value and “grow-with-child” potential outrank durability and price; (2) mixed-methods analysis with 226 caregivers and 15 interviews links immersive, temperament-specific play to longer attachment; (3) a literature-driven framework maps the ICID-adapted Big Five onto 15 toy-design categories, yielding temperament-responsive personas; and (4) clustering, logistic-regression and Random-Forest models (n = 214) demonstrate that the resulting “ToyMatch” recommendation approach markedly improves trait–feature alignment, especially for Extraversion, Conscientiousness and Openness, as confirmed by SHAP interpretability plots. A mobile interface concept—still to be prototyped—will translate the model into practice by posing 5-10 temperament questions and returning three optimised toy suggestions. The findings underscore (i) the centrality of developmental benefits in caregivers’ sustainability logic, (ii) temperament as a lever for emotional durability, and (iii) the current e-commerce gap in communicating long-term use value. By combining temperament psychology, design semantics and decision science, the study offers actionable pathways for designers, retailers and policy-makers to curb premature toy discard. Future work will expand the dataset cross-culturally, build a working prototype for empirical validation, and probe correlations between specific toy categories and child temperaments.