After implementation of routine infant MenC vaccination, MenB remains a serious cause of meningococcal disease, yet to be targeted by vaccination programs in several countries. This study (NCT01339923) investigated the immunogenicity and safety of MenC CRM-conjugated vaccine (MenC-CRM) concomitantly administered with MenB vaccine (4CMenB). Methods: Infants (N = 251) were randomised 1:1 to receive 4CMenB and MenC-CRM (Group 1) or MenCCRM alone (Group 2) at 3 and 5 months (M3, M5) and a booster at 12 months of age (M12), and pneumococcal vaccine at M3, M5, M7, M12. Antibody responses to meningococcal vaccines were measured at M3, M6, M12, and M13. Non-inferiority of MenC-CRM response in Group 1 vs Group 2 was demonstrated at M6 and M13, if the lower limit of the 95% confidence interval (LL95%CI) of the difference in percentage of infants with hSBA titres 1:8 was > 10%. Sufficiency of MenB response was achieved if LL95% CI of the percentage of infants with hSBA titres 1:4 against fHbp, NadA and PorA strains was 70% at M6 or 75% at M13. Adverse events (AEs) were collected for 7 days post-vaccination, and serious AEs (SAEs) and medically attended AEs throughout the study. Results: Non-inferiority of MenC response in Group 1 vs Group 2 (LL95%CI 6.4% [M6]; 5.2% [M13]) and sufficiency of MenB response in Group 1 (LL95%CI 92%, 90%, 89% [M6]; 97%, 92%, 93% [M13] against fHbp, NadA, PorA, respectively) were demonstrated. Higher rates of mild to moderate solicited AEs were reported in Group 1. Unsolicited AEs and SAEs incidences were similar across groups. Conclusions: Concomitant administration of MenC-CRM and 4CMenB in infants was immunogenic, resulting in non-inferior responses against MenC compared to MenC-CRM alone and demonstration of sufficient immune response to MenB, after primary and booster vaccination. Reactogenicity was higher for concomitant vaccines administration, but no safety concerns were identified.