Several foreign missions in China raised the Ukrainian flag, or displayed its image in posters and lights, following the February 2022 invasion.
Ukrainian officials have long been calling on Beijing to use its influence in Russia to help end the war.
China now appears to be stepping in, a year into the war in Ukraine, sensing that the West is not as unified as it appears.
Xi hass sought to position China as a potential mediator in the conflict but is seen by the West as favoring Russia.
Blinken said China's political and material support for Russia goes against Washington's interests.
"There was a very thorough exchange of views, a serious conversation in the informal part," the Kremlin spokesperson said, referring to Monday's meeting.
Xi was expected to press Beijing's role as a potential peacemaker in the conflict following the release of a 12-point plan
Reports say that the sides will discuss Russian-Chinese cooperation in the international arena. Important bilateral documents are supposed to be signed or at least come out of these meetings.
Xi has been seeking to present China as a global peacemaker and project it as a responsible great power.
The US has been engaging in suppression and containment of China rather than fair or rule-based competition, Foreign Minister Qin Gang stated on Tuesday.