<p>Bedtime problems and night wakings are highly prevalent in infants. This study assessed the real-world effectiveness of an mHealth behavioral sleep intervention (Customized Sleep Profile; CSP). Caregivers (83.9% mothers) of 404 infants (age 6 to 11.9 m, M = 8.32 m, 51.2% male) used the CSP (free and publicly available behavioral sleep intervention delivered via smartphone application, Johnson's® Bedtime® Baby Sleep App). Caregivers completed the Brief Infant Sleep Questionnaire-Revised (BISQ-R) at baseline and again 4 to 28 days later. Changes in sleep patterns were analyzed, based on sleep problem status (problem versus no problem sleepers; PS; NPS). Sleep onset latency improved in both groups. Earlier bedtimes, longer continuous stretches of sleep, as well as decreased number and duration of night wakings, were evident in the PS group only. The BISQ-R Total score, total nighttime sleep, and total 24-hour sleep time improved for both groups, with a greater change for the PS group. Further, caregivers of infants in the PS group decreased feeding (bedtime and overnight) and picking up overnight, and perceived better sleep. Bedtime routine regularity, bedtime difficulty, sleep onset difficulty, and caregiver confidence improved for both groups, with the PS group showing a greater magnitude of change. Thus, a real-world, publicly available, mHealth behavioral sleep intervention was associated with improved outcomes for older infants. Intervention recommendations resulted in changes in caregivers' behavior and improvements in caregiver-reported sleep outcomes in infants, in as few as 4 days.</p>