Background: Studies in Nigeria and elsewhere in sub-Saharan Africa have explored factors influencing usage of intermittent preventive treatment of malaria in pregnancy (IPTp). However, most of the studies are not model or theory-based, which provides less satisfactory guidance to malaria control programming. This study fills the knowledge gap by adapting the Andersen’s behavioural model of health services use to IPTp usage in Nigeria.Methods: This study adopted a cross-sectional design that utilised secondary data extracted from the 2018 Nigeria Demographic and Health Survey (NDHS). A weighted sample of 4,772 women who had deliveries in the past year preceding the survey was analysed. The outcome variable was usage of IPTp dichotomised into optimal or otherwise. The explanatory variables cut across individual and community levels, and were divided into predisposing, enabling and need factors in line with the theoretical constructs of the Andersen model. Two multilevel mixed-effects logistic regression models were fitted to identify the factors influencing optimal usage of IPTp. Analyses were performed using Stata 14. Statistical significance was set at 5%. Results: The realised level of optimal IPTp usage was 21.8%. The factors that either predispose or enables a pregnant woman to take optimal doses of IPTp are age, education, being employed, being autonomous on own healthcare, health insurance enrolment, partner education, receiving antenatal care in public health facility, rural residence, being resident in northern geo-political zones, community literacy level, and community perception of the consequences of malaria. Two significant need factors affecting optimal usage of IPTp are timing of first antenatal care contact and actual sleeping under mosquito bed net. Conclusion: Optimal usage of IPTp is low among pregnant women in Nigeria. There is need to devise additional public health education programme promoting IPTp usage through the formation of Advocacy, Communication and Social Mobilisation (ACSM) core group in every ward in all the local government areas in the country. In addition, health planners in the country should adopt the use of the Andersen model for assessing key determinants of IPTp usage among childbearing women in the country.