The main aim of this study was to test whether mothers\' (n = 116) and fathers\' (n = 116) mind-mindedness predicts infants\' physiological emotion regulation (heart rate variability; HRV) across the first year of life. Three hypotheses were examined: (a) parents\' mind-mindedness at 4 and 12 months predicts infants\' HRV at 12 months over and above infants\' initial HRV levels at 4 months, (b) mothers\' and fathers\' mind-mindedness independently predict infant HRV, and (c) the effects of mind-mindedness on infant HRV (partially) operate via parenting behaviour. Infants\' HRV was assessed during rest and a stranger approach. Mind-mindedness was assessed by calculating the proportions of appropriate and non-attuned mind-related comments during free-play interactions, and parenting quality was observed at 4 and 12 months in the same interactions. Path analyses showed that mothers\' appropriate mind-related comments at 4 and 12 months predicted higher baseline HRV at 12 months, whereas mothers\' non-attuned comments predicted lower baseline HRV at 12 months. Similar, but concurrent, relations were found for fathers\' appropriate and non-attuned mind-related comments and infant baseline HRV at 12 months. In addition, fathers\' appropriate mind-related comments showed an indirect association with infant baseline HRV at 12 months via fathers\' parenting quality. With regard to infant HRV reactivity during the stranger approach, mothers\' appropriate mind-related comments at 4 months and fathers\' non-attuned mind-related comments at 12 months predicted a larger HRV decline during the stranger approach at 12 months. Infants\' HRV at 4 months did not predict parents\' later mind-mindedness. The results indicate that mothers\' and fathers\' appropriate and non-attuned mind-related speech uniquely impacts the development of infants\' physiological emotion regulation.