Background Kangaroo mother care (KMC) has been proven to decrease rates of morbidity and mortality among premature and low-birth-weight infants. Thus, this study aimed to obtain baseline data regarding KMC knowledge, attitudes, and practices (KAP) among nursing staff caring for mothers and newborns in a hospital in Indonesia. Methods This cross-sectional study included 65 participants from three hospital wards at Koja District Hospital, North Jakarta. Participants included 29 perinatal ward nurses, 21 postnatal ward nurses and midwives, and 15 labor ward midwives. Data on KAP of KMC were collected using a self-administered questionnaire with closed-ended questions. Each questionnaire can be completed in approximately 1 hour. Results Among the included nursing staff, 12.3% (8/65) were determined to have received specific training on KMC, whereas 21.5% (14/65) had received more general training that included KMC content. About 46.2% of the nursing staff had good knowledge concerning KMC, 98.5% had good knowledge of KMC benefits, and 100% had a positive attitude toward KMC. All perinatal ward nurses had some experience assisting and implementing KMC. Some KAP that were observed among the nursing staff included lack of knowledge about the eligible infant weight for KMC and weight gain of infants receiving KMC, lack of education/ training about KMC, and concerns regarding necessary equipment in KMC wards. Conclusions This study identified several issues that need to be addressed, including knowledge of feeding and weight gain, workload, incubator use, and the need for well-equipped KMC wards. We recommend that hospitals improve their nursing staff's knowledge of KMC and establish well-equipped KMC wards.