The postpartum period may pose a considerable challenge for both parent sleep and sexual activity. This study assessed the links between partnered sexual frequency and satisfaction postpartum and parent sleep, infant sleep, parent nighttime caregiving, and parent-infant room sharing. Participants were 897 parents of infants aged 1–18-months (M = 8.8 ± 4.3, 49% girls). Parents completed an online survey about their sexual frequency and satisfaction, sleep, relationship satisfaction, depression, and demographic characteristics. Infant sleep and parent nighttime crib visits were measured objectively using auto-videosomnography during 2-weeks, with 8,460 nights assessed. Results indicated that the frequency of partnered sexual activity was 3.8 ± 4.2 times per month. Frequency of sexual activity increased with infant age, yet increases beyond the first 6 months postpartum were non-significant. Adjusted GEE modeling revealed that more parent nighttime crib visits were significantly associated with lower sexual frequency, regardless of infant age. Other parent and infant sleep-related factors were not significantly linked with sexual frequency in adjusted models. Moreover, sexual satisfaction was not associated with parent nighttime caregiving, parent or infant sleep, or parent-infant sleeping arrangements in adjusted models, suggesting that it may not be susceptible to the effects of disrupted sleep in the postpartum period. These findings suggest that it is not infant or parent sleep disruption per se, but rather parent nighttime engagement with the infant that is associated with parent sexual activity frequency. Longitudinal investigations are warranted to examine the directional pathways of these links.