Banksy posted a picture on Instagram of the artwork, a gymnast doing a handstand amid debris, in Borodyanka.
Murals spotted in and around Ukraine's capital Kyiv had led to speculation the anonymous artist was working in the war-torn country.
Another, not officially claimed, depicts a man resembling Vladimir Putin being defeated at Judo by a child.
The graffiti artist posted three images of the gymnast mural in the wreckage left by Russian shelling, with a caption merely stating "Borodyanka, Ukraine".
Borodyanka was one of the places hardest hit by Russia's bombardment of Ukraine in the immediate aftermath of the 24 February invasion.
Russian soldiers occupied the town - located around 30 miles (48km) north west of Ukraine's capital Kyiv - for weeks in the initial phase of the war, before it was eventually liberated by Ukraine in April.
A second piece in Borodyanka, which has not been confirmed to be by Banksy, depicts a man resembling Vladimir Putin being flipped during a judo match with a young boy. The Russian president is a judo black belt and noted admirer of the martial art.
The town, which is on the outskirts of Kyiv, was the site of a notorious massacre of hundreds of civilians by occupying Russian troops.
A fourth work, which also resembles Banksy's signature spray-painted style, portrays two children sitting on a metal tank trap and using it as a seesaw spray painted onto a concrete defensive block in Kyiv.
Banksy is one of the world's most famous artists - while also remaining completely anonymous.
He rose to fame with stencilled designs around Bristol in the early 1990s. But over the years, examples of his work have popped up in Paris, New York and Park City, in Utah
Often described as "elusive" and "secretive" by the press, the "guerrilla street artist" has a legion of fans that includes A-list celebrities.