Is there a relationship between maternal sensitivity (MS) and infant-directed speech (IDS)? This study assessed whether mothers who sensitively respond to their infants’ vocalizations also exhibit more salient pitch exaggeration in their speech. We observed 29 mother-infant dyads during free-play sessions when infants were 5 months old and 10 months old, analyzing both the vocalization types and the acoustic characteristics of maternal speech. Results showed that mothers significantly exaggerated the pitch contours of their IDS when responding sensitively to their infants’ object-directed vocalizations (ODVs) as compared to their nonsensitive IDS. In contrast, mothers did not exaggerate their IDS when responding to infants’ undirected vocalizations (UDVs). Overall, mothers provided a higher proportion of sensitive responses to the babbling of 10-month-old infants as compared to five-month-olds, indicating a heightened sensitivity to prelinguistic vocalizing as infants grow older. However, neither maternal sensitivity nor IDS features were found to predict language production and comprehension scores at 18 months, though there were only 5 dyads who completed the language questionnaire. In conclusion, maternal sensitivity and infant-directed speech are closely tied, and this relationship is dynamic and context-dependent.