The postnatal period is an underserved aspect of maternity care, potentially worsened by the COVID-19 pandemic. This study aims to identify postnatal care (PNC) use by health personnel within the 42 days of childbirth among postpartum mothers in Thailand. This web-based, cross-sectional study was conducted from July to October 2021 (n = 840). Multiple binary and ordinal logistic regressions were conducted to predict three outcome variables (≥2 times, ≥3 times, or level of PNC use). Women who received PNC were in low numbers (≥2: 30.7% and (≥3: 12.9%), while 54.4% of women reported no barriers to access PNC, and 31.9% reported barriers, including worries over COVID-19 infection, followed by movement restrictions imposed by the government (11.7%) and the closure of healthcare centers (10%). Women working in a self-employed capacity, living in urban areas, and undergoing a Caesarean section with no/less worry about COVID-19 infection were more likely to utilize postnatal care (≥2 or number of PNC). This study provides timely information, revealing that a relatively low percentage of postpartum women received PNC, particularly among the socially deprived group. Since the fear of COVID infection is listed as a major barrier, the provision of PNC services, including a telehealth program should be considered.