An expanded garden center at the front of the store, including a Florida room, could open as early as October.
"Wal-Mart is going into the Super Centers for customer convenience and one-stop shopping," said Rob Reck, assistant manager of the Chambersburg store.
The expanded Wal-Mart will employ close to 450 people.
The new Super Center is expected to maintain the current 24-hour-a-day schedule, Reck said.
The new grocery store will offer customers a full array of food and merchandise, including a produce department, bakery and deli, said Keith Morris, Wal-Mart's director of community affairs at its Arkansas headquarters.
"We're averaging 100 Super Centers per year. It evolved into a major growth vehicle for the company," Morris said.
Wal-Mart first tested the Super Center concept - one stop shopping with all needs under one roof - at a store in Washington, Mo., in 1988, Morris said.
"It exceeded our expectations in leaps and bounds," he said.
Although the Chambersburg area has several large supermarkets, including a new Weis Market superstore scheduled to open this fall on Wayne Avenue, Wal-Mart doesn't intend to directly compete with them, Morris said.
The Super Center will simply provide the store's existing customers with the option to buy their groceries there, he said.
"We're not looking to take in any more customers than what we have now," he said.
Wal-Mart Super Centers typically attract more people from outside the local area, he added.
There are nine Wal-Mart Super Centers in Pennsylvania.