The global COVID-19 pandemic is predicted to compromise the achievement of global reproductive, maternal, and newborn health (RMNH) targets. The objective of this study was to determine the health facility (HF) preparedness for RMNH service delivery during the outbreak from the perspective of RMNH providers and to determine what factors significantly predict this. An anonymous cross-sectional online survey of RMNH providers was conducted from to July 1-21, 2020 in Lagos State, Nigeria. We conducted a descriptive and ordinal regression analysis, with RMNH worker perception of HF preparedness for RMNH service delivery during the outbreak as the dependent variable. In all, 256 RMNH workers participated, 35.2% reported that RMNH services were unavailable at some time since March 2020, 87.1% felt work-related burnout, 97.7% were concerned about the availability of personal protective equipment (PPE) and related guidelines, and only 11.7% were satisfied with the preparedness of their HFs. Our final model was a statistically significant predictor of RMNH worker perception of HF preparedness explaining 54.7% of the variation observed. The most significant contribution to the model was communication by HF management (likelihood ratio chi-square [LRCS]: 87.94, P < 0.001) and the availability of PPE and COVID-19 guidelines (LRCS: 15.43, P < 0.001). A one-unit increase in the level of concern about the availability of PPE and COVID-19 guidelines would increase the odds of observing a higher category of satisfaction with HF COVID-19 preparedness. Adequate support of RMNH providers, particularly provision of PPE and guidelines, and appropriate communications about COVID-19 should be prioritized as part of HF preparedness.