Lewis formally announced he would challenge Republican incumbent Dawn Addiego, NJ.com reported.
While not detailing his platform, Lewis said: "When I was athlete I also loved my competition. I think I have a better message."
Addressing questions about his residency, Lewis said he first purchased a house in New Jersey in 2005 and registered to vote Monday, NJ.com said.
"I'm going to be the people's candidate," Lewis said. "I'm going to knock on as many doors as I can."
Lewis, 49, has never run for office.
He gained fame in 1984 when he won four gold medals at the Los Angeles Olympics. He also won two golds and a silver at the 1988 Seoul Olympics, two golds at the 1992 Barcelona Olympics and one gold for the long jump at the 1996 Atlanta Olympics.
The senatorial district leans Republican but state Democratic leaders said they thought a famous and wealthy candidate such as Louis could be competitive.