Concerned Corio locals spotted the two boys, aged just two and 18 months, in Stead Park about 3pm yesterday.
It is believed the boys left their nearby home when their mum was asleep on the couch and the front door was unlocked.
The good Samaritans dressed the boys in spare clothes, including pink tracksuit pants and a blue jumper, to keep them warm on the chilly 13C day and called police.
Officers collected the boys before 4pm and took them to the Corio police station.
The toddlers were given a bottle of formula and toys to keep them entertained while a search for any relatives was undertaken.
After a frantic search to locate family members, the police released the images of the boys to the media in the hope that someone would recognise the pair.
Family members did not contact police to report the toddlers missing.
But the boys’ mother was found asleep on the couch after officers doorknocked the area near where the boys were spotted.
“The police found the door to the home unlocked and a woman asleep on the couch who did not know where her children were,” a police spokesman said.
“It looks like the mother nodded off at some point in the afternoon and the boys took a stroll to the park together.”
The source said the single mother was a stay-at-home mum and did not appear to be affected by drugs or alcohol when she was found by police.
The mother went to the police station. She has not been charged with an offence.