Objectives <p>Limited data exists on endoscopic retrograde cholangiopancreatography (ERCP) for children with common bile duct microdilation (CBDM). We evaluate the benefits of ERCP applications in CBDM, with or without pancreaticobiliary maljunction (PBM).</p> Methods <p>Retrospective analysis of 36 children with CBDM undergoing therapeutic ERCP. Patients were stratified by the presence (PBM group, <i>n</i> = 15) or absence (non-PBM group, <i>n</i> = 21) of PBM. Data included demographics, clinical/imaging/endoscopic findings, and post-ERCP outcomes.</p> Results <p>A total of 36 children underwent therapeutic ERCP procedures with a success rate of 100%. In the non-PBM group (<i>n</i> = 21), ERCP significantly reduced liver enzyme and bilirubin levels, and the bile duct diameter decreased significantly at 1 week and 3 months postoperatively. In the PBM group (<i>n</i> = 15), ERCP significantly reduced liver enzyme levels. During follow-up, most children showed improvement in general condition after ERCP regardless of PBM presence, with an overall treatment effectiveness rate of 77.8% (28/36). Both the frequency and severity of abdominal pain significantly decreased. The postoperative complication rate of ERCP was 19.4% (7/36). In the non-PBM group, 1 child (4.8%) underwent laparoscopic hepaticojejunostomy (LH) due to recurrent pancreatitis and new common bile duct stones after ERCP, while in the PBM group, 6 children (40%) underwent LH due to recurrent pancreatitis, bile duct stones, and bile duct dilation exceeding 10&#xa0;mm.</p> Conclusion <p>ERCP is an effective primary treatment for CBDM children without PBM and serves as a beneficial transitional intervention for those with concomitant PBM. Children with CBDM, regardless of PBM, can derive clinical benefit from ERCP.</p>