According to the Ukrainian Air Force, the Su-34 was shot down at around 4am (local time) while carrying out a mission to drop a bomb that guided the city of Zaporizhzhia.
Ukraine insists the Russian plane participated in airstrikes targeting civil infrastructure and residential areas before hitting air defense ground.
Russia has not yet responded officially.
The Su-34 is a medium-range fighter - bombing aircraft developed on the Su-27 platform, capable of carrying many types of weapons, from guided bombs to air-to-ground and air-to-air missiles.
The plane has played a key role in Russian operations, especially airstrikes on targets deep in Ukraine.
Zaporizhzhia has been continuously attacked by airstrikes in recent days.
On September 22, the city was attacked by many powerful bombs, causing a major fire and damaging homes.
Just two days later, Russian unmanned aerial vehicles (UAVs) continued to airstrike in the area. At least six bombs hit civil infrastructure and buildings, adding to the security tensions, local officials said.
Experts say the Su-34, if confirmed, shootout will be a significant success for Ukrainian air defense in the context of Moscow increasing airstrikes.
However, this event also shows that the air war in southern Ukraine continues to develop in a complex and risky manner.
