In the GOP primary statewide, Olens took 214,026 votes, or 39.7 percent of the vote, over Smith's 166,114 votes, or 30.8 percent.
Former U.S. Attorney Max Wood of Macon came in last in the GOP field with 29.5 percent of the vote.
But Olens was the clear GOP winner among Cobb County voters, winning 42,240 votes, well ahead of both opponents, who earned about 7,000 votes each in the county.
Candidates must win 50 percent plus one vote to win outright. Olens and Smith will meet in a runoff on Aug. 10.
In the Democratic race, former prosecutor Hodges scored a resounding victory Tuesday - across Georgia and in Cobb - over rival state Rep. Rob Teilhet, of Smyrna.
Statewide, Hodges took 209,420 votes, or 65.4 percent, over Teilhet's 110,558 votes, or 34.6 percent.
And in Teilhet's home county, Cobb, he only mustered 7,966 votes to Hodges' 11,854.
Olens said the high of the campaign has "definitely been seeing every part of this beautiful state and meeting many wonderful and engaged citizens who care about the future of our great state. The low is the time away from your family. We should appreciate all candidates who make that sacrifice in the interest of better government."
Would Olens have done anything differently?
"Probably not. I am extremely proud of the positive and energized campaign we have won and I'm grateful and humbled by the scores of volunteers who have given their valuable time in this pursuit," he said.
Dr. Kerwin Swint, an elections specialist at Kennesaw State University, said the Republican nominee should have an edge on Nov. 2.
"Republicans are energized this year, nationally and locally, and if the nominee is Olens he will have substantial financial resources to draw on," Swint said.
"Sam Olens has definitely been the front-runner for most of the campaign, and has been expected to win. Some doubt crept in recently, however, with renewed emphasis on his past as a Democrat in Georgia. The entrance of Preston Smith into the race brought with it the possibility of a runoff. And it was Smith who pressed Olens on the issue of his past ties to the Democrats and to Bill Clinton's 1992 candidacy. Olens did a good job of responding, reminding everyone that many successful Republicans were Democrats at one time, including Ronald Reagan. Olens should win, even if it goes to a runoff," Swint said.
Olens, 53, and his wife, and Lisa Olens have two children. They live in east Cobb.
Teilhet, 36, an attorney who lives in Smyrna with his wife, Heather, and their twin daughters, was gracious in his concession speech.
"Tonight Ken Hodges has won a great victory. I wish nothing but the best for Ken, his family and his supporters. I'll be forever grateful for my supporters and staff that have worked tirelessly with me for the last 16 months of this campaign," Teilhet said.
Teilhet generated controversy when he ran an emotional ad featuring a grieving mother who claimed Hodges made mistakes in a high-profile case involving her son's death. Hodges countered that Teilhet was exploiting a victim for political gain.
"I think the voters of this state certainly rejected negative politics and they decided this was about experience, not about politics," Hodges said after his victory Tuesday night. "They thought it was about seeking justice - not about seeking office."