Public service quality is an important indicator of good governance and public accountability. However, maladministration, particularly the abuse of authority, remains a significant challenge in ensuring effective and citizen-oriented public services in Indonesia. This study aims to analyze the implementation of supervision conducted by the Ombudsman of the Republic of Indonesia Representative Office of Banten Province in preventing and addressing abuse of authority in public services based on the author's internship experience. This study employed a qualitative descriptive approach using participant observation, document analysis, and literature review. Primary data were collected through direct involvement in complaint administration, preparation of Document Examination Reports (LHPD), public service monitoring, meeting documentation, and other administrative activities during the internship. The findings reveal that the Ombudsman implements an integrated supervisory mechanism consisting of complaint reception, administrative verification, substantive examination, coordination with relevant institutions, and corrective recommendations. In addition, preventive supervision is carried out through public education, monitoring compliance with public service standards, and institutional collaboration to reduce maladministration. The internship enhanced the researcher's understanding of public service supervision while improving analytical, administrative, communication, and teamwork skills. Nevertheless, challenges remain, including limited public awareness of the Ombudsman's functions, incomplete supporting evidence in complaints, and varying institutional responsiveness. This study concludes that the Ombudsman Representative Office of Banten Province plays a strategic role in promoting accountability, preventing abuse of authority, and strengthening good governance through independent external supervision of public service delivery.