Iconicity plays an important role in language acquisition and cognition. This study aimed to better understand the use of three types of vocal iconicity in language input and child production: sound effects (e.g., making the sound of eating), onomatopoeia (e.g., meow), and iconic prosody (e.g., faaar). We coded these aspects in a corpus of Chinese adult-directed speech (ADS) and child-directed speech (CDS), in which mothers semi-spontaneously told the same story to an adult and their 18-month-old (N = 21) or 24-month-old (N = 19) children. We examined whether mothers’ vocal iconicity differs between CDS and ADS and how it emerges in child production. We found that (1) mothers used significantly more sound effects and iconic prosody, but not onomatopoeias, in CDS compared to ADS; (2) In CDS, the proportions of the three types of iconicity ranked as iconic prosody>sound effects>onomatopoeias, whereas the proportions for children emerged as sound effects>iconic prosody and onomatopoeias; (3) Chinese children aged 18 or 24 months produced little onomatopoeia and iconic prosody (except for one instance at 24 months). In conclusion, iconicity is more prevalent in CDS than in ADS, and iconic prosody is an advanced prosodic skill that is not typically developed by two-year-old children.