The win marked a dramatic comeback for Moore who was twice removed from his position as chief justice – once for refusing to remove a 5,200-pound granite Ten Commandments monument from the lobby of the state judicial building, and once for telling the state’s probate judges to refuse to grant marriage licenses to gay couples.
Moore denied he urged the judges to defy the U.S. Supreme Court order in 2016.
Moore, never one to shy away from publicly expressing his views, has on many occasions expressed strong anti-gay sentiments. He promoted "birtherism," the theory that former President Barack Obama was not born in America, and suggested that the 9/11 attacks were a punishment from God.
"Because you have despised His word and trust in perverseness and oppression, and say thereon ... therefore this iniquity will be to you as a breach ready to fall, swell out in a high wall, whose breaking cometh suddenly at an instance,'" Moore said, quoting the Bible. He added, "Sounds a little bit like the Pentagon, whose breaking came suddenly at an instance, doesn't it?"
At a political rally in Fairhope, Alabama, on Monday, Moore produced a handgun from his pocket to illustrate his support for the Second Amendment.
Since the September runoff, Moore has faced a growing number of allegations of improper sexual contact with teenagers when he was in his thirties. Moore has denied all of the charges.
In November, the Republican National Committee cut financial support to Moore over the allegations. In early December, the RNC resumed the support after Trump endorsed Moore.
Moore will face Democratic nominee and former U.S. Attorney Doug Jones in the general election on Dec. 12.
From The Associated Press, here are some things to know about Moore:
West Point grad, Vietnam vet
Moore grew up in rural Alabama in a house that did not have indoor plumbing. He graduated from the U.S. Military Academy at West Point, a place he said he was inspired to attend after watching the movie "The Long Gray Line." Moore served as a commander of a military police unit in Vietnam. Moore said the troops sometimes referred to him as "Captain America" because of his strict adherence to military code.
Kickboxer, ranch hand and poet
After losing a 1982 race for circuit judge, Moore left Alabama for Texas and competed as a kickboxer. He also spent a year working on a cattle ranch in Australia, before returning to the law. He has also dabbled in poetry. In a poem titled "America the Beautiful" Moore wrote "America the Beautiful, or so you used to be, Land of the Pilgrims' pride, I'm glad they're not here to see, Babies piled in Dumpsters, abortion on demand, Oh, sweet land of liberty, your house is on the sand."
'Acknowledgement of God'
A stalwart of the religious right, Moore has long argued that the nation is forgetting its Christian roots and has made the "acknowledgement of God" his signature issue. In campaign speeches, he has criticized federal court rulings that he said prevented football coaches from praying on the 50-yard line and forced judges to recognize marriage between a "man and a man."
Homosexuality an 'inherent evil'
Moore wrote in a 2002 concurring opinion in a child custody case that there was a presumption that the mother is unfit because she was in a relationship with a woman. He said homosexuality is "an inherent evil against which children must be protected." On the campaign trail in 2012, he predicted that gay marriage would be the ultimate destruction of the country. He was a vocal critic of the Obergefell v. Hodges decision that legalized same-sex marriage.
GOP voice for sentencing reform
Moore has been an advocate for sentencing reform in the state. In special writings as chief justice, he criticized mandatory minimum sentences that he said tied judges' hands. In 2015, he criticized a life sentence given to a man in his 70s after police found a marijuana growing operation in his home. The man said he was growing the marijuana for personal use. Moore also criticized a habitual offender life sentence given to a man who was attempting to shoplift a nail gun.
'Message to the Swamp'
Moore has received the backing of a number of anti-establishment forces in the U.S. Senate race. Former White House strategist Steve Bannon and the pro-Trump Great America Alliance lined up behind Moore. Former Alaska Gov. Sarah Palin said in a rally last week that Moore's election would send the "loudest message to the swamp." While President Donald Trump endorsed Strange in the race, he said he would support Moore in December if he won Tuesday's runoff.