King was born in Elba, Alabama where his father was a real estate agent. King credits his interest in politics to being told at age 10 by his father that a canceled family vacation was the fault of President Jimmy Carter. He is a Baptist. King received his undergraduate degree from Troy University and is a 1994 graduate of the University of Alabama Law School.

After his appointment as attorney general in 2004, King replaced former Alabama Attorney General Bill Pryor as defendant in the case of Williams v. Morgan. This case unsuccessfully sought to enjoin the state of Alabama from enforcing the Anti-Obscenity Enforcement Act of 1998, a law prohibiting the sale of any “device designed or marketed as useful primarily for the stimulation of human genital organs,” commonly known as “sex toys.” As the state's attorney general, King defended the law. King’s stance was praised by religious conservatives, but it also subjected him to considerable criticism from editorial Writers and civil liberties advocates, one of which mailed King an inflatable pig sex toy.

King brought attention to the need for new laws requiring the tracking of released sex offenders by wearing an electronic monitoring bracelet (the kind used by parolees and others under judicial monitoring) during the 2005 Legislative Session. He continued to wear the bracelet until the legislature passed tougher laws requiring the monitoring of parolees and convicted sex offenders.

In late 2006, King was forced to recuse his entire office from the ongoing investigation of abuses in the Alabama community college system when it emerged that he had asked community college chancellor Roy Johnson to hire the mother of one of King's employees. It later emerged that King had also asked Johnson for community college system financial support for Victims of Crime and Leniency (VOCAL), an international advocacy group composed of Alabama families who have been addressing crime victims' needs —and a group which has supported King. King's office continued to provide investigative support, which resulted in a guilty plea by Johnson in the related federal investigation.

Later in 2007, Anthony Castaldo, a former investigator with the attorney general's office was charged with perjury by District Attorney David Barber. During the trial, Castaldo submitted an affidavit that King ordered him to investigate a Birmingham-area judge for political reasons. Castaldo also alleged that he was punished when a year-long investigation showed no evidence of wrongdoing by the judge. After other investigators took over the case, King secured an indictment against the judge, but the charges against the judge were later dismissed. Castaldo was acquitted of the perjury charge and later resigned his position within the attorney general's office.

In September 2008, in the aftermath of hurricanes Gustav and Ike, King's office began processing more than 2,500 complaints regarding gasoline prices under Alabama's price gouging statutes. A month later, a King spokesman said the investigations remained "ongoing" as the prices begin to return to lower levels.

After having been mentioned as a possible gubernatorial candidate in 2010, King announced his re-election campaign for attorney general on March 9, 2009. King was an early supporter of the 2008 presidential campaign of Arizona Senator John McCain and served as the Alabama chair of the McCain campaign. King was defeated by Luther Strange in the GOP primary on June 1, 2010.

On May 21, 2010, the Alabama Supreme Court handed down a finalized ruling that answered lingering questions in the gambling debate between King and Governor Riley. The court's ruling had two components: first, that the governor does indeed maintain the constitutional authority to approve law enforcement actions without the approval of the attorney general, and second, that any law enforcement operation conceived and operated by the governor cannot be seized by the attorney general, and any previously seized operations must be immediately turned over to the governor's appointed special counsel. The relevant section of the Supreme Court ruling states that "we hold that the actions of the attorneys and other officers authorized by Governor Riley to act in this case are not “nullities,” despite the lack of approval by the attorney general and the district attorney, and that the attorney general may not take over or countermand the litigation efforts of those officers in either the trial court or in this Court. The counsel authorized by the governor have the right to represent the state in this case and to see it through to completion."