The 78-22 vote to confirm the man described as a conservative with a quiet manner included all Senate Republicans and about half of the Democrats.
President Bush had nominated Roberts to replace retiring Supreme Court Justice Sandra Day O'Connor. Following the death of Chief Justice William Rehnquist from thyroid cancer, the president elevated Roberts' nomination to the chief justice position.
Roberts at one time clerked for Rehnquist, and in accepting the president's nomination, said, "I am very much aware that if I am confirmed I would succeed a man I deeply respect and admire, a man who has been very kind to me for 25 years."
Roberts also served as deputy to then-Solicitor General Kenneth Starr at the Justice Department. During his career, he argued 39 cases before the high court in the public and private sector, and won 25.
In 2001, President Bush nominated Roberts to the U.S. Court of Appeals for the D.C. Circuit, and he was confirmed by the Senate in 2003. Roberts also had been nominated to the seat under the previous Bush administration but never received a Senate vote.
Roberts' relatively short stint on the circuit court meant he had few published opinions to act as fodder for his opponents, so his confirmation was generally assumed even at the start of the process.
During Roberts' confirmation hearings, senators tried to draw out his opinions on issues ranging from affirmative action to abortion. In general, the candidate addressed questions through the prism of legal precedent but did not answer specifics.
Senate Judiciary Committee Chairman Arlen Specter, R-Pa., asked Roberts about his views of the landmark 1973 decision Roe v. Wade that legalized abortion. Specter, a supporter of abortion rights, asked if the ruling was a "super-duper precedent" in light of efforts to overturn it.
Roberts said, "It's settled as a precedent of the court, entitled to respect under principles of stare decisis," a Latin term for the doctrine that says courts are bound by previous decisions or precedents.
Sen. Edward Kennedy, D-Mass., Asked what minorities and other groups of Americans who have faced discrimination in the past could find in his record to assure them that he would not set back the progress they have made toward equal opportunity. "Senator, there's a great deal in my background that you could look to in that respect," Roberts said. He added that he believes in affirmative action and has volunteered in a program to help prepare minority students for the rigors of law school.
Some of the Republicans on the committee used the hearings to point out other issues with the current Supreme Court. Sen. Jon Kyle of Arizona said he was troubled by "the Supreme Court's reliance, or even reference to, foreign law to determine the meaning of the United States Constitution."
Roberts answered that foreign precedent "allows the judge to incorporate his or her own personal preferences, cloak them with the authority of precedent -- because they're finding precedent in foreign law -- and use that to determine the meaning of the Constitution."
"And I think that's a misuse of precedent, not a correct use of precedent," he said.
Roberts stressed at his hearings that as chief justice, he would seek to build larger and clearer majorities in Supreme Court decisions. He also said he would be guided by the law and not his personal opinion on matters.
Before becoming an appellate judge, Roberts practiced law at Hogan & Hartson in Washington, D.C. from 1986-1989 and again in 1993-2003.
Between 1989 and 1993, he was the principal deputy solicitor general in the first Bush administration, helping formulate the administration's position in Supreme Court cases, reported the Washington Post.
During the Reagan administration, he served as an aide to Attorney General William French Smith from 1981-1982 and as an aide to White House counsel Fred Fielding from 1982-1986.
Roberts graduated from Harvard College and Harvard Law School.
His votes on the D.C. Circuit Court have generally fallen on the conservative side, but not always, according to the Legal Times.
He ruled in favor of a criminal defendant who challenged his sentence in a fraud case, in United States v. Mellon, while another conservative judge dissented.
In the July 2004 case Barbour v. Washington Metropolitan Area Transit Authority, Roberts joined a Clinton appointee in deciding that sovereign immunity did not bar a D.C. employee with bipolar disorder from suing the transit authority under federal laws banning discrimination against the disabled.
But in another WMATA case, Hedgepeth v. WMATA, Roberts voted along with the other judges to uphold the arrest, handcuffing and detention of a 12-year-old girl for eating a French fry inside a D.C. Metrorail station.
"No one is very happy about the events that led to this litigation," Roberts said, according to the Legal Times, but he ruled that the police did not violate the girls' Fourth or Fifth Amendment rights.
In another case, Roberts wrote a dissenting opinion that suggested Congress might lack the power under the Constitution's Commerce Clause to regulate the treatment of a certain species of wildlife, reported the Washington Post.
And in Rust v. Sullivan, a 1991 case, he successfully helped argue that doctors and clinics receiving federal funds may not talk to patients about abortion, according to Slate.
As a private attorney, he discussed the close of the 1996-97 Supreme Court term with its then-5-4 divide, telling the NewsHour, "I do think there's a solid majority on the court for the proposition that federalism has to be taken seriously; that states do retain rights under our federal system. ... I think by enforcing these structural limitations, states have their powers and rights. The federal government is limited. The end objective, as the framers intended, is to protect individual rights."
Roberts was born in 1955 in Buffalo, N.Y., and has a wife and two children.