Vitalii Sapylo, 21, played in the youth team for Ukrainian second division side Karpaty Lviv, whilst Dmytro Martynenko, 25, was an amateur footballer for FC Gostomel.
They have become football's first reported losses in this war.
The news was announced by FIFPRO, whose statement read: "Our thoughts are with the families, friends, and teammates of young Ukrainian footballers Vitalii Sapylo (21) and Dmytro Martynenko (25), football's first reported losses in this war.
"May they both rest in peace."
Sapylo's team, Karpaty Lviv, added: "We cherish the eternal memory of this hero."
Russia's invasion of Ukraine has led to football's governing bodies making a series of big decisions.
Saint Petersburg has been replaced as host city for the Champions League final, whilst FIFA and UEFA have suspended all Russian teams from competing in any international or domestic tournaments.
Russia has also been banned from competing in the World Cup and its athletes in other sports are unlikely to be able to compete.
The passing of Sapylo and Martynenko came as former Ukraine footballer and manager Andriy Shevchenko called for peace with Russia.
Ahead of the Milan derby on Tuesday night he sent a video message asking for Italians to help.
The former Chelsea striker said: "Dear Italian friends, I ask you from San Siro to give your support for peace in Ukraine.
"The Ukrainian people want peace, because peace has no borders, because what unites us must be stronger than what divides us.
"Let us stop this war together. I embrace you all."