Zelensky said the remaining 10% of the agreement to end nearly four years of conflict would "determine the fate of peace, the fate of Ukraine and Europe".
In his own New Year speech, Russian President Vladimir Putin told his troops that "we believe in you and our victory".
Earlier on Wednesday, Moscow also released what it said was evidence of Ukraine using drones to target Putin's private home on Lake Valdai in north-west Russia, allegations Kyiv has strenuously denied.
