Police say the unit is climate controlled, but people who rent other spaces say there's no water, electricity or thermostat in the units.
The children are now in the custody of Division of Youth and Family Services while their mother is behind bars.
The 5 and 10-year-old boys were found inside the cramped and cluttered storage unit in Mercer County.
During an unrelated arrest, police say their mother admitted that they were living in these conditions for more than a month.
Junior Brady says he met Sheena Johnson and her kids about three weeks ago and felt something just wasn't right.
"You thought she was living there?" Eyewitness News asked.
"Yeah," Brady said.
"Why?" Eyewitness News said.
"Because I never saw a car, never saw a car," Brady said.
The 27 year old mother was arrested Thursday morning for allegedly slashing her ex-boyfriend's tires and violating a restraining order.
During processing, investigators say she admitted the family was living at the Extra Space Storage Facility in Ewing.
Police say the kids didn't look hurt or malnourished when they found them, so they got them food and took them to the hospital to get checked out.
Bernice Watson rents a space there and can't believe they were living like this.
"I can't even think about something living in a storage unit. I have four kids myself, total shock," Watson said.
The children's mother is charged with endangering the welfare of a child.
No bail has been set.