Biden was born in Scranton, Pennsylvania, and lived there for ten years before moving with his family to Delaware. He became a lawyer in 1969 and was elected to the New Castle County Council in 1970.

Biden attended the Archmere Academy in Claymont where he was a standout halfback/wide receiver on the high school football team; he helped lead a perennially losing team to an undefeated season in his senior year. He played on the baseball team as well. During these years, he participated in an anti-segregation sit-in at a Wilmington theater. Academically, he was an above-average student, was considered a natural leader among the students, and was elected class president during his junior and senior years. He graduated in 1961.

He earned his bachelor's in 1965 from the University of Delaware, with a double major in history and political science, graduating with a class rank of 506 out of 688. His classmates were impressed by his cramming abilities, and he played halfback with the Blue Hens freshman football team. In 1964, while on spring break in the Bahamas, he met and began dating Neilia Hunter, who was from an affluent background in Skaneateles, New York, and attended Syracuse University. He told her that he aimed to become a senator by the age of 30 and then president. He dropped a junior year plan to play for the varsity football team as a defensive back, enabling him to spend more time visiting out of state with her.

Biden's entry into the 1972 U.S. Senate election in Delaware presented a unique circumstance. Longtime Delaware political figure and Republican incumbent Senator J. Caleb Boggs was considering retirement, which would likely have left U.S. Representative Pete du Pont and Wilmington Mayor Harry G. Haskell Jr. in a divisive primary fight. To avoid that, U.S. President Richard Nixon helped convince Boggs to run again with full party support. No other Democrat wanted to run against Boggs. Biden's campaign had virtually no money and was given no chance of winning. It was managed by his sister Valerie Biden Owens (who would go on to manage his future campaigns) and staffed by other family members, and relied upon handed-out newsprint position papers and meeting voters face-to-face; the small size of the state and lack of a major media market made the approach feasible. He did receive some assistance from the AFL–CIO and Democratic pollster Patrick Caddell. His campaign issues focused on withdrawal from Vietnam, the environment, civil rights, mass transit, more equitable taxation, health care, the public's dissatisfaction with politics-as-usual, and "change". During the summer, he trailed by almost 30 percentage points, but his energy level, his attractive young family, and his ability to connect with voters' emotions gave the surging Biden an advantage over the ready-to-retire Boggs. He won the November 7, 1972 election in an upset by a margin of 3,162 votes.

He was first elected to the U.S. Senate in 1972 when he became the sixth-youngest senator in American history.

On December 18, 1972, a few weeks after the election, Biden's wife and one-year-old daughter Naomi were killed in an automobile accident while Christmas shopping in Hockessin, Delaware. Neilia Biden's station wagon was hit by a tractor-trailer truck as she pulled out from an intersection. Biden's sons Beau and Hunter survived the accident and were taken to the hospital in fair condition, Beau with a broken leg and other wounds, and Hunter with a minor skull fracture and other head injuries. Doctors soon said both would make full recoveries. Biden considered resigning to care for them, but was persuaded not to by Senate Majority Leader Mike Mansfield. In later years, Biden commented that the truck driver had been drinking alcohol before the collision, but these allegations have been denied by the driver's family and were never substantiated by the police.

Biden was a long-time member of the U.S. Senate Committee on the Judiciary. He chaired it from 1987 until 1995 and he served as ranking minority member on it from 1981 until 1987 and again from 1995 until 1997.

The 1988 presidential campaign of Joe Biden, the longtime Democratic United States Senator from Delaware and eventual 47th Vice President of the United States, began in June 1987. He ran for President of the United States in the 1988 United States presidential election. He was considered one of the potentially strongest candidates in the field. However, in September 1987, newspaper stories stated he had plagiarized a speech by British politician Neil Kinnock. Other allegations of past law school plagiarism and exaggerating his academic record soon followed. Biden withdrew from the race later that month.

Biden was named the Benjamin Franklin Presidential Practice professor at the University of Pennsylvania, where he intended to focus on foreign policy, diplomacy, and national security while leading the Penn Biden Center for Diplomacy and Global Engagement. He also wanted to pursue his "cancer moonshot" agenda, calling the fight against cancer "the only bipartisan thing left in America" in March 2017.

Biden declared his candidacy for president on January 31, 2007, after having discussed running for months prior. Biden made a formal announcement to Tim Russert on Meet the Press, stating he would "be the best Biden I can be". In January 2006, Delaware newspaper columnist Harry F. Themal wrote that Biden "occupies the sensible center of the Democratic Party". Themal concludes that this is the position Biden desires and that in a campaign "he plans to stress the dangers to the security of the average American, not just from the terrorist threat, but from the lack of health assistance, crime, and energy dependence on unstable parts of the world".

Soon after the election, he was appointed the chairman of president-elect Obama's transition team. During the transition phase of the Obama administration, Biden said he was in daily meetings with Obama and that McCain was still his friend. The U.S. Secret Service codename given to Biden is "Celtic", referencing his Irish roots.

Biden was the running mate of Democratic presidential nominee Barack Obama and became the first Roman Catholic to serve as vice president of the United States.

Biden declared his candidacy for president on January 31, 2007, after having discussed running for months prior. Biden made a formal announcement to Tim Russert on Meet the Press, stating he would "be the best Biden I can be." In January 2006, Delaware newspaper columnist Harry F. Themal wrote that Biden "occupies the sensible center of the Democratic Party." Thermal concludes that this is the position Biden desires and that in a campaign "he plans to stress the dangers to the security of the average American, not just from the terrorist threat, but from the lack of health assistance, crime, and energy dependence on unstable parts of the world."

On November 4, 2008, Biden was elected Vice President of the United States as Obama's running mate.

At noon on January 20, 2009, Joe Biden became the 47th vice president of the United States, sworn into the office by Supreme Court Justice John Paul Stevens. Biden is the first United States vice president from Delaware and the first Roman Catholic to attain that office.

In October 2010, Biden stated that Obama had asked him to remain as his running mate for the 2012 presidential election. With Obama's popularity on the decline, however, in late 2011 White House Chief of Staff William M. Daley conducted some secret polling and focus group research into the idea of Secretary of State Clinton replacing Biden on the ticket. The notion was dropped when the results showed no appreciable improvement for Obama, and White House officials later said that Obama had never entertained the idea.

Biden was inaugurated to a second term in the early morning of January 20, 2013, at a small ceremony in his official residence with Justice Sonia Sotomayor presiding (a public ceremony took place on January 21). He continued to be at the forefront as, in the wake of the Sandy Hook Elementary School shooting, the Obama administration put forth executive orders and proposed legislation towards new gun control measures (the legislation failed to pass).

On May 30, 2015, Biden's son, Beau Biden, died at age 46 after having battled brain cancer for several years. In a statement, the Vice President's office said, "The entire Biden family is saddened beyond words." The nature and seriousness of the illness had not been previously disclosed to the public, and Biden had quietly reduced his public schedule in order to spend more time with his son. At the time of his death, Beau Biden had been widely seen as the frontrunner to be the Democratic nominee for Governor of Delaware in 2016.

The 2020 presidential campaign of Joe Biden began on April 25, 2019, when Biden released a video announcing his candidacy in the 2020 Democratic party presidential primaries. Joe Biden, the former vice president of the United States and a former U.S. senator from Delaware, had been the subject of widespread speculation as a potential 2020 candidate after declining to be a candidate in the 2016 election. As a former vice president, Biden entered the race with very high name recognition. From his campaign announcement until late September, he was generally considered the front runner of the race and led the national primary in most major polls.