The choice is widely seen in Washington as shoring up the Democratic Party ticket's foreign policy credentials in the battle against Republican John McCain.
The 65-year-old Biden is currently in his sixth term in the US Senate and is Delaware's longest-serving senator. He is the chairman of the foreign relations committee in the Congress.
He is considered a strong supporter of Israel. In a march 2007 interview with the US-based Jewish cable television network Shalom TV he declared: "I am a Zionist."
He described Israel as "the single greatest strength America has in the Middle East."
He travelled with Barack Obama to Israel in late July, when Obama promised strong support for Israel against the threat from Iran, and said he would strongly support the Mideast peace process soon after he takes office.
In the same interview, Biden revealed that his son is married to a Jewish woman, of the Berger family from Delaware, and that he had participated in a Passover Seder at their house.
He added that "probably my most poignant Seder memory is not with the Bergers, but what happened right after I came back from meeting Golda Meir (in 1973). I had predicted that something was going on in Egypt. And I remember people talking about what it meant to them if Israel were actually defeated."
Like Obama, Biden supports direct talks with Iran. "I believe the United States should agree to directly engage Iran, first in the context of the 'P-5 plus 1', and ultimately country-to-country, just as we did with North Korea," Biden said in an early July press statement.
The 'P-5 plus 1' refers to the five permanent UN Security Council members plus Germany.
"The net effect of demanding preconditions that Iran rejects is this: We get no results and Iran gets closer to the bomb," he said."