Infant social–emotional development may be impacted by the COVID‐19 pandemic. This study investigated associations between maternal pre‐ and postnatal pandemic‐related concerns and social–emotional developmental risk. Data, collected in 2020–2021, came from 220 mothers (87% white, 6% Hispanic, 1% Black, 3% Asian, 1% American Indian, Mage = 32.46 years), and infants (53.18% male, Mage = 12.98 months) in the United States. Maternal postnatal pandemic‐related concerns were associated with total risk scores (B = 6.09, p‐value <.001) and offspring risk of scoring positive for problems related to inflexibility (B = 4.07, p‐value = .006). The total score association was moderated by self‐reported social support. Infants may be detrimentally impacted by the pandemic via maternal pandemic‐related concerns. Maternal social support may buffer infants.