Mayor Martin J. Walsh announced Monday that he will reappoint Michael O’Neill to the Boston School Committee as it prepares to finalize a long-term plan to address aging school buildings and declining enrollment.

O’Neill, who has been chairman of the board for the last four years, was originally appointed by former mayor Thomas M. Menino in 2008. He is the longest-serving member of the seven-person committee.

“I am honored to re-appoint Michael O’Neill to the Boston School Committee,’’ Walsh said in a statement. “Michael is a proven leader who understands the importance of moving the school district forward and broadening quality educational opportunity for all students across the city. I look forward to his continued work with the district and the community to improve our schools.’’

Walsh plans to swear in O’Neill for his new term Wednesday at 5:30 p.m. O’Neill’s current term expired Monday.

The School Committee will decide whether to reelect O’Neill as chairman at its organizational meeting on Thursday at 4 p.m. The board will also select a vice chairman, a position that has been held by Hardin Coleman. O’Neill and Coleman are the only two members originally appointed by Menino.

O’Neill, a Boston Latin School graduate, is the executive vice president of financial services at 451 Marketing in Boston. He lives in Charlestown. During his time on the board, O’Neill has overseen the hiring of a new superintendent, Tommy Chang, and has helped guide the district through painful budget cuts that have included some school closings.

“I thank the Mayor for this opportunity and I greatly appreciate his commitment to the students of Boston,’’ O’Neill said in a statement. “The Boston School Committee has enjoyed working closely with the Mayor and his team and I look forward to continuing our work together to improve the lives and futures of the 57,000 students in the Boston Public Schools.’’

The School Committee, which oversees the system’s $1 billion annual budget and sets district policies, has a number of pressing issues ahead. It is in the midst of negotiating a new contract with the teachers union to replace an agreement that expired last August. The committee is also navigating tight finances while trying to pursue new initiatives, such as an extended day in elementary, middle, and K-8 schools.

All the while, the School Committee’s effort to develop a long-term facilities plan has raised concerns among parents, teachers, and students about the prospect of more school closings. The school system has lost hundreds of students in the middle and upper grades as it faces intensifying competition from a growing number of charter schools.

It’s unclear when a decision will be made about school closings.

James Vaznis can be reached at james.vaznis@globe.com. Follow him on Twitter @globevaznis.