Black individuals in the US experience sleep disparities beginning in infancy and continuing throughout the lifespan, suggesting early interventions are needed to improve sleep. To investigate whether a responsive parenting (RP) intervention for Black mothers improves infant sleep and increases responsive sleep parenting practices. This is a post hoc secondary analysis of the Sleep SAAF (Strong African American Families) study, a randomized clinical trial comparing an RP intervention with a safety control condition over the first 16 weeks post partum. Data were collected between spring 2018 and summer 2021. Families were recruited from the mother-infant nursery at Augusta University Medical Center, Augusta, Georgia, and completed home visits at 1, 3, 8, and 16 weeks post partum. Primiparous Black mother-infant dyads were screened for eligibility using medical records. Results were analyzed on an intention-to-treat model. Data were analyzed from March 2022 to January 2023. The RP intervention curriculum focused on infant sleep, soothing and crying, and feeding. The control group received a safety intervention. Community research associates delivered the interventions during home visits at 3 and 8 weeks post partum. The primary end point was infant sleep duration at 16 weeks. Mothers reported on bedtime routine and sleep behaviors, infant sleep duration, and nighttime waking and feeding at 8 and 16 weeks post partum using questionnaires. A total of 212 Black mothers (mean [SD] age, 22.7 [4.5] years) were randomized, including 208 mothers (98.6%) who identified as non-Hispanic and 3 mothers (1.4%) who identified as Hispanic; 108 mothers were randomized to the RP group and 104 mothers were randomized to the control group. At 16 weeks post partum, infants in the RP group had longer reported nighttime sleep duration (mean difference, 40 [95% CI, 3 to 77] minutes), longer total sleep duration (mean difference, 73 [95% CI, 14 to 131] minutes), fewer nighttime wakings (mean difference, -0.4 [95% CI, -0.6 to -0.1] wakings), and greater likelihood of meeting guidelines of at least 12 hours of total sleep per day (risk ratio [RR], 1.4 [95% CI, 95% CI, 1.1 to 1.8]) than controls. Relative to controls, mothers in the RP group more frequently reported engaging in some RP practices, including giving the baby a few minutes to fall back asleep on their own (RR, 1.6 [95% CI, 1.0 to 2.6]) and being less likely to feed their baby as the last activity before bed (RR, 0.5 [95% CI, 0.3 to 0.8]). This secondary analysis of a randomized clinical trial found that an RP intervention for Black families improved infant sleep and increased some responsive sleep parenting practices. ClinicalTrials.gov Identifier: NCT03505203.