Raffensperger, a state lawmaker from suburban Atlanta, defeated former Democratic congressman John Barrow to become Georgia's top elections official, the office vacated by Gov.-elect Brian Kemp.
At his victory party late Tuesday, Raffensperger told supporters he would faithfully carry out elections in Georgia.
"I'm going to make sure that elections are clean, fair and accurate," he said. "And that's the No. 1 priority as your next secretary of state."
Floyd County voters chose Raffensperger — by a slightly bigger margin than they did in the general election.
On Tuesday, Raffensperger won 72.45 percent of the 10,481 votes cast locally, beating Barrow 7,594 to 2,887. In November, he took 69.47 percent.
Turnout countywide was 20.03 percent, down considerably from the 57.79 percent of registered voters who went to the polls Nov. 6.
In the Public Service Commission runoff, Republican Chuck Eaton was re-elected to a third term. He defeated Democrat Lindy Miller for the commission's District 3 seat.
Eaton was again the local favorite with 71.02 percent of the vote, pulling down 7,422 votes to Miller's 3,029.
Floyd County Elections Board Chair Steve Miller said the totals in both races are unofficial and he expects some adjustment when the races are certified.
A consent order valid only for this election allows all absentee ballots to be counted as long as they are postmarked by Tuesday and received by Friday. Normally, the extended deadline applies just to military and other overseas ballots.
Miller said they plan to count the rest of the absentee and validated provisional ballots Friday and the secretary of state is scheduled to certify the statewide vote Monday.
However, he said state officials may decide to bump that out another day because the U.S. Postal Service is closed today — a National Day of Mourning for the funeral of former President George H.W. Bush.
The secretary of state runoff campaign played out against the backdrop of Democratic accusations that Kemp used his position to suppress minority turnout and increase his own odds of victory. Kemp insists that's false, pointing to large increases in voter registration on his watch and record turnout in the Nov. 6 midterms.
Raffensperger finished the three-way general election race ahead of Barrow, but just shy of the 50 percent of the vote needed to avoid a runoff. Issues that dogged Kemp in the general election — Georgia's strict "exact match" policy for confirming voters' identities and reports that the state's aging electronic voting system was vulnerable to hackers — became the focus of the race to succeed him.
Both Raffensperger and Barrow promised to replace Georgia's voting machines with a system that produces paper records that could be used to audit elections if needed.
Meanwhile, Raffensperger pledged to continue Kemp's practices of strictly enforcing voter ID laws and pruning registration rolls of inactive voters to prevent voting fraud. Barrow said Georgia needed to make it less difficult to cast ballots.
President Donald Trump endorsed Raffensperger with a tweet calling the Republican "tough on Crime and Borders." The secretary of state oversees elections, professional licensing and business incorporation in Georgia. The office has no law enforcement role.
Kemp's Democratic rival for governor, Stacey Abrams, urged voters to support Barrow during the same speech in which she acknowledged defeat and announced she would sue to challenge the way Georgia runs elections. That suit was filed in federal court last week.
Barrow also won an endorsement from Smythe DuVal, the Libertarian candidate whose distant third-place finish in November forced the race into overtime.
Raffensperger served four years in the Georgia House before running for statewide office. He will take over as secretary of state in January from Robyn Crittenden, who was appointed to the office when Kemp stepped aside last month.
Barrow sought a political comeback after losing his U.S. House seat in 2014. He served a decade in Congress representing a large swath of eastern Georgia that included Athens, Augusta and Savannah.
Staff writer Diane Wagner contributed to this report