Malaria in pregnancy remains a significant public health concern due to its detrimental effects on both maternal and fetal health. This study assessed the prevalence of malaria and its associated factors among pregnant women in the Rivers East Senatorial District of Rivers State using a descriptive cross-sectional design. The study population comprised 133,545 registered pregnant women, from which 360 respondents were selected through a multistage sampling technique. Data were collected using the Assessment of Malaria and Associated Factors Proforma (AMaaFP) and analyzed with the Statistical Package for Social Sciences (SPSS) version 27.0, employing descriptive statistics and logistic regression at a 0.05 level of significance. The findings revealed that 26.4% of the respondents tested positive for malaria, while 73.6% were malaria-negative, with higher prevalence observed among women in the first and second trimesters, those younger than 20 years, primigravidae, users of intermittent preventive treatment with sulfadoxine–pyrimethamine, and women with multiple gestations. Bivariate analysis showed statistically significant associations between malaria in pregnancy and gestational age, maternal age, use of intermittent preventive treatment with sulfadoxine–pyrimethamine, and multiple gestation (p < 0.05). The study concluded that malaria prevalence among pregnant women in the Rivers East Senatorial District remains high and recommended that the State Ministry of Health strengthen malaria prevention strategies, particularly through the routine free distribution of insecticide-treated bed nets at antenatal clinics to ensure early and consistent use by pregnant women.