"I think the government has made considerable progress in the first year, it's remarkable," he said.
Hashim Thaci, Kosovo's prime minister, said Biden' visit was a "reconfirmation of powerful support from the US for the progress that we have achieved in Kosovo."
The US vice president is regarded as one of Washington's strongest advocates of the independence of ethnic Albanian-majority Kosovo, which declared its secession from Serbia in February last year.
But, along with his backing of Nato's 1999 bombing campaign to end ethnic violence in the province, his stance has led to strong anger towards the US among Serbs in the region.
Around 1,000 Serbians staged a protest in Mitrovica, an ethnically divided town in Kosovo, over Biden's visit to the province on Thursday.
"We wish to draw attention to the fact that America is not our friend and we cannot expect anything good" from Biden's visit, Radovan Nicic, a Serbian leader, said.
Serbs, who account for about 100,000 of Kosovo's population of two million, consider the territory their country's medieval heartland.
On Wednesday, Biden told Serbia he did not expect the country to recognise Kosovo, or that it would be a precondition for eligibility to join the EU.
Biden will spend his final night in former Yugoslavia in Kosovo's southeast at Camp Bondsteel, one of the largest US military bases outside of the United States, before travelling onto Lebanon.