Korea adopted a 10-valent pneumococcal conjugate vaccination in 2010 for children aged 6 weeks to 5 years to protect against invasive illness caused by Streptococcus pneumoniae serotypes 1, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, 23F, and cross-reactive 19A. The goal of this 6-year real-world research of 646 healthy Korean children immunized in normal practice from 16 sites is to monitor vaccine safety in accordance with Ministry of Food and Drug Safety requirements. Around 50% had a previous or current medical problem, 19.3% had an existing ailment, and 7.6% got concomitant medication). In all, 489 adverse events (AEs) were documented in 274 newborns; 86% were mild, the remainder were moderate, and just three were serious. The majority of adverse events (97.8%) were unrelated to vaccination; one instance of injection-site edema and fever was associated, two cases of fever were probably related, five cases of fever, and one case each of diarrhea and coughing was potentially related. None of the major adverse events were linked to vaccination. None of the 11 adverse drug reactions (ADRs) in 10 patients were severe. In all, 263 participants (40.7%) were given medicine (mostly antibiotics or antipyretics) to address an AE, with 6 subjects receiving therapy for an ADR. There was no difference in the occurrence of AEs based on age, gender, or concurrent immunization. Subjects who had a pre-existing medical condition had substantially higher AEs than those who did not have any problems (p = 0.03), however, there were no differences in ADRs. For Korean children, four doses of PHiD-CV immunization appear to have a clinically acceptable safety profile.