Bill Fletcher was sworn in Tuesday afternoon.
He will serve the remainder of the term previously held by former board member Debra Goldman, which expires in November.
The board picked him two weeks ago by a vote of 6 to 2.
Fletcher previously served three terms on the board of education from 1993 to 2005.
On the agenda Tuesday, the school board is also tackling the budget as they look to build new schools to keep up with growth.