Painted using dark red ochre pigment, the life-sized picture of the Sulawesi warty pig appears to be part of a narrative scene.
The picture was found in the Leang Tedongnge cave in a remote valley on the island of Sulawesi.
It provides the earliest evidence of human settlement of the region.
"The people who made it were fully modern, they were just like us, they had all of the capacity and the tools to do any painting that they liked," said Maxime Aubert, the co-author of the report published in Science Advances journal.
A dating specialist, Aubert had identified a calcite deposit that had formed on top of the painting, and used Uranium-series isotope dating to determine that the deposit was 45,500 years old.
This makes the artwork at least that old. "But it could be much older because the dating that we're using only dates the calcite on top of it," he added.
The report says that the painting, which measures 136cm by 54cm (53in by 21in), depicts a pig with horn-like facial warts characteristic of adult males of the species.
There are two hand prints above the back of the pig, which also appears to be facing two other pigs that are only partially preserved.
Co-author Adam Brumm said: "The pig appears to be observing a fight or social interaction between two other warty pigs."
To make the hand prints, the artists would have had to place their hands on a surface before spitting pigment over it, the researchers said. The team hopes to try and extract DNA samples from the residual saliva as well.
The painting may be the world's oldest art depicting a figure, but it is not the oldest manmade art.
In South Africa, a hashtag-like doodle created 73,000 years ago is believed to be the oldest known drawing.
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