Background: Maternal and child characteristics have been reported to be associated with the complete immunization of children. This study aimed to assess maternal and child characteristics associated with the immunization status of children in a rural community in Rivers State. Methods: A descriptive cross-sectional study was conducted among 410 mothers with children ranging in age from 9 to 23 months residing in Rumuji town between October and December 2022. Semi-structured, interviewer-administered questionnaires with open- and closed-ended questions were used for data collection. The immunization cards of the children were used to determine their immunization status, and IBM SPSS version 25 was used for data analysis. Results: 238 mothers (54.8%) were mainly between the ages of 21 and 30, with a mean age of 28.20 ± 6.90 years. 315 (83.3%) of the children were females between the ages of 14 and 18 months, with a mean age of 15.70 ±7.42 months. The maternal and child factors associated with up-to-date immunization in the study were: mothers aged 21 to 30 years, married, had secondary education, were unemployed, had 1 to 3 children, attended an antenatal clinic in a health facility, delivered at home, had a childbirth order of 1st and 2nd, and had female children. 295 (72.0%) of the children were up-to-date immunized, 84 (20.5%) were partially immunized, and 31 (7.6%) were not immunized. Conclusion: The proportion of children with up-to-date immunization was high, although it was not up to the recommended 80% district coverage by the World Health Organization. There is a need to intensify routine and outreach immunization services, especially in the rural communities of Rivers State.