In Mariupol, southeastern Ukraine, occupied by Russian forces, the Moscow-appointed authorities erected a 20-metre Christmas tree.
The tree was transported to the city all the way from St Petersburg.
However, officials said there will be no mass holiday celebrations in this city heavily destroyed by Russian shelling this year.
In nearby Kherson, at least were seven killed and 58 injured in a strike on Christmas eve.
Russian shells rained around a busy market in the southern port city, starting a fire.
The city was recaptured by Kyiv's forces in November. Despite Russia's retreat from the city, Kherson remains within reach of Moscow's weaponry and under constant threat.
But Kherson has been regularly bombarded ever since, with a heavy toll on civilians and the power supply to the city.
December 24 also marks 10 months since the start of the Russian invasion.
Ukrainian President Volodymyr Zelenskyy called for togetherness during his holiday address on Christmas Eve on Saturday.
Zelenskyy admitted the holiday would have a "bitter" taste amid the ongoing war with Russia and for those absent from the dinner table.
Fighting still rages on around the eastern Kharkiv region and around Bakhmut, where Ukrainian and Russian forces have clashed in a fierce, months-long battle.