"It's a pivotal moment, not only in Mideast history, but in history," Biden said at a public lecture series in Kentucky the first official US reaction on Mubarak's resignation.
"We have said from the beginning, as an administration, that this unrest, that the future of Egypt will be determined by the Egyptian people," Biden said.
US President Barack Obama, was scheduled to address the press on the developments in Egypt later in the day.
He was originally scheduled to speak at 1-30 pm local time, which has now been postponed, the timing of which has not been announced yet.
"Even in this contentious political climate in which we work, on this issue, the United States has largely spoken with one voice, Democrats and Republicans alike, speaking with the same voice," Biden said.
"This unity has been important, and it will be even more important in these delicate and fateful days ahead," said the Vice President.
Earlier, Obama had asked for "concrete" change in Egypt, a staunch US ally, after Mubarak wrong-footed the world by clinging to power.
Obama issued a strongly-worded statement after a day of drama in Egyptian capital Cairo in which hopes that embattled Mubarak would step down were replaced by fury as he only went as far as ceding some authority to Vice President Omar Suleiman.
"The Egyptian people have been told that there was a transition of authority, but it is not yet clear that this transition is immediate, meaningful or sufficient," Obama said.
Earlier, Mubarak, who ruled Egypt with an iron hand for over three decades, stepped down as President today and handed over power to the army capitulating under mass protests sweeping the country's streets for the last 18 days.
Mubarak resigned and handed over power to the military, announced the recently appointed vice president Omar Sulaiman on state television.
Tahrir Square, the epicentre of the anti-government protests, erupted in joy with tens of thousands of people shouting ''Egypt is Free".
The end of a despotic regime in most populous Arab nation came one week after the protesters set a deadline of ''Departure Friday'' for 82-year- old Mubarak to step down as President.