We are delighted to present the proceedings of the 12th Asia-Paci?c Network Operations and Management Symposium (APNOMS 2009), which was held in Jeju, Korea, during September 23-25, 2009. Recently, various convergences in wired and wireless networks, and conv- gence of telecommunications and broadcastings, are taking place for ubiquitous multimedia service provisioning. For example, broadband IP/MPLS wired n- works are actively converged with IEEE 802.11e wireless LAN, IEEE 802.16 Wireless MAN, 3G/4G wireless cellular networks, and direct multimedia bro- cast (DMB) networks. For e?cient support of service provisioning for ubiq- tous multimedia services on the broadband convergencenetworks, well-designed and implemented network operations and management functions with Q- guaranteed tra?c engineering are essential. The converged network will open the way for a new world with emerging new businesses and computing services. The Organizing Committee (OC) selected "Management Enabling the Future Internet for Changing Business and New Computing Services" as the timely theme of APNOMS 2009. Contributions from academia, industry and research institutions met these challengeswith173papersubmissions,fromwhich41high-qualitypapers(23.7% of the submissions) were selected for technical sessions as full papers, and 32 papers were selected as short papers. In addition, we had nine papers in - novation sessions for on-going research. Diverse topics were covered, including Tra?c Trace Engineering, Con?guration and Fault Management, Management of IP-Based Networks, Autonomous and Distributed Control, Sensor Network and P2P Management, Converged Networks and Tra?c Engineering, SLA and QoS Management, Active and Security Management, Wireless and Mobile N- work Management, and Security Management.