Roman Hryshchuk, a member of the Ukrainian parliament, also shared a picture of Zelensky waving his hand in Kherson, commenting: "Zelensky is in Kherson!"
The Ukrainian military entered Kherson on Friday after Russia's withdrawal from the region.
Zelensky and leaders of Western countries hailed it as a major Ukrainian victory.
Zelensky said late on Sunday that Ukrainians are increasingly confident about achieving victory over Russia in the ongoing war.
"All of us already feel the approach of our victory. Because we preserve our unity and know that we are rightfully on our land," Zelenskyy said in a video message posted on Telegram.
The Kremlin on Monday insisted that Kherson was still part of Russia after Ukrainian leader Volodymyr Zelensky visited the southern city from which Moscow's troops retreated last week.
"We leave this without comment," Kremlin spokesman Dmitry Peskov said of Zelensky's visit to Kherson, adding however: "You know, this territory is part of the Russian Federation."