So much for Virginia turning blue.

With a record-breaking turnout in a governor’s election Tuesday, political newcomer Glenn A. Youngkin swept to a narrow but decisive victory over former Gov. Terry R. McAuliffe, who hoped to be only the second governor since 1869 to serve two terms.

The 54-year-old Republican’s victory, which came with the backing of former President Donald Trump, will end eight years of Democratic control of the Governor’s Mansion.

It also makes Mr. Youngkin a rising star in the GOP given his ability walk the political tightrope between Trump supporters and suburban residents and gain votes from both factions of the party.

With most voters casting a straight party ticket, Mr. Youngkin’s win also enabled a GOP sweep for the state’s top three offices. Winsome E. Sears secured the No. 2 post of lieutenant governor — the first woman and first woman of color to do so—and Republican Delegate Jason S. Miyares, a Cuban American, won attorney general. He bested Mark R. Herring, who has held the attorney general’s post for eight years and hoped secure a third term.

Unofficial results indicate more than 3.2 million votes were cast on Election Day and in early voting. That is 500,000 more than in the last gubernatorial election in 2017, and about 1.3 million votes less than were cast in Virginia in the 2020 presidential contest.

Mr. Youngkin captured 1.65 million votes, or slightly more than 50 percent, according to preliminary results that show him with a 79,000-vote lead over Mr. McAuliffe, who also set a record with 1.57 million votes.

Mr. McAuliffe received 500,000 more votes than in 2013, when he won the governorship. It also beat the record 1.4 million votes current Democratic Gov. Ralph S. Northam received in 2017.

Liberation Party candidate Princess L. Blanding received only about 22,500 votes that were too few to affect Tuesday’s result.

Delegate Hala S. Ayala, the Democratic candidate for lieutenant governor, and Attorney General Herring both set records for their vote totals as well in their second-place finishes.

Both Mr. McAuliffe and Mr. Youngkin raised nearly $60 million apiece, setting a record for spending in a governor’s race, with Mr. Youngkin providing $20 million to his campaign. Though stinging, the Republican victory represented the restoration of a familiar four-decade pattern in this state—the election of a governor from the opposite party of the sitting president. Mr. McAuliffe’s 2013 victory after President Barack Obama’s re-election was the only break. Based on a survey, the AP found that men, rural and small town voters and white evangelicals were squarely with Mr. Youngkin, while Mr. McAuliffe was the choice for Black voters, moderates, college graduates and voters under age 45.

A wealthy former co-chief executive of the Carlyle Group investment firm, Mr. Youngkin promised to get to work quickly, saying he would “work in real people’s time, not government time.”

The Virginia vote was widely regarded as an early referendum on Joe Biden’s presidency, and along with results from New Jersey, where Republicans also were doing well, sent shockwaves through Democratic ranks ahead of the 2022 midterm elections.

Mr. McAuliffe, who easily beat four opponents in a June primary to become the Democratic standard bearer, appeared to hold a 15-percentage point lead over Mr. Youngkin when the contest began, according to early polls.

But that lead began to shrink, and as the election loomed, most analysts suggested that trends favored Mr. Youngkin and Republicans. Republican internal polls by late September were suggesting their candidates could sweep.

Mr. McAuliffe, at the time, said he expected the race to be close, but still expected to pull it out as he had in his first run for Virginia’s chief executive.

What is clear is that Mr. McAuliffe’s campaign of trying to tie Mr. Youngkin to Mr. Trump did not work well enough and did not turn off Youngkin voters.

Democratic achievements in expanding voting rights, legalizing marijuana and abolishing the death penalty got far less attention, although Mr. McAuliffe repeatedly warned that the state government’s ability to safeguard abortion and the expansion of voting rights could be at risk in a Youngkin administration.

Unlike Mr. McAuliffe, who had major Democratic figures such as former President Obama campaign with him in the state, Mr. Youngkin largely campaigned alone, portraying himself as a Virginian and promising tax cuts and a better economy.

“I’m not a politician. I’m a homegrown Virginian, and I’ve spent the last 30 years raising my family, serving in our church, building business and creating jobs,” he stated on his website. “I’m guided by my faith, my values and unshakeable belief that Virginia should be the best.”

During the campaign, he was successful in tapping into con- servative parental resentment against public school systems as he promised to ban teaching of critical race theory, which isn’t taught in schools.

“From the farms of the Shenandoah Valley to the docks and shipyards of Hampton Roads to the coalfields in Southwest Virginia, from the banks of the James River to the memorials in Arlington National Cemetery, this is our Virginia to build together,” Mr. Youngkin said.

Mr. McAuliffe could not immediately reach Mr. Youngkin, but left a voicemail concession, his campaign later said.

Despite being held at arms-length, Mr. Trump sought to take credit. In a statement, he noted that his supporters turned out in force, adding, “Without you, (Mr. Youngkin) would not have been close to winning. The MAGA movement is bigger and stronger than ever before.”