Antenatal care (ANC) and facility delivery are essential maternal health services, but uptake remains low in north-western Nigeria. This study aimed to assess the psychosocial influences on pregnancy and childbirth behaviours in Nigeria. Data were from a cross-sectional population-based survey of randomly sampled women with a child under 2 years conducted in Kebbi, Sokoto and Zamfara states of north-western Nigeria in September 2019. Women were asked about their maternal health behaviours during their last pregnancy. Psychosocial metrics were developed using the Ideation Model of Strategic Communication and Behaviour Change. Predicted probabilities for visiting ANC four or more times (ANC4+) and giving birth in a facility were derived using mixed-effects logistic regression models adjusted for ideational and socio-demographic variables. Among the 3039 sample women, 23.6% (95% CI: 18.0–30.3%) attended ANC4+ times and 15.5% (95% CI: 11.8–20.1%) gave birth in a facility. Among women who did not attend ANC4+ times or have a facility-based delivery during their last pregnancy, the most commonly cited reasons for non-use were lack of perceived need (42% and 67%, respectively) and spousal opposition (25% and 27%, respectively). Women who knew any ANC benefit or the recommended number of ANC visits were 3.2 and 2.1 times more likely to attend ANC4+ times, respectively. Women who held positive views about health facilities for childbirth had 1.2 and 2.6 times higher likelihood of attending ANC4+ times and having a facility delivery, respectively, while women who believed ANC was only for sickness or pregnancy complications had a 17% lower likelihood of attending ANC4+ times. Self-efficacy and supportive spousal influence were also significantly associated with both outcomes. To improve pregnancy and childbirth practices in north-western Nigeria, Social and Behavioural Change programmes could address a range of psychosocial factors across cognitive, emotional and social domains which have been found in this study to be significantly associated with pregnancy and childbirth behaviours: raising knowledge and dispelling myths, building women’s confidence to access services, engaging spousal support in decision-making and improving perceived (and actual) maternal health services quality.