Byrne, a former 2010 gubernatorial hopeful who lost that GOP primary, took about 33 percent while Young, who primaried Bonner in 2012 and lost, took 25 percent of the vote.
Operatives expected the primary to head to a runoff between Byrne, who has widely been seen as the front-runner because of his fundraising prowess and strong name recognition, and a Tea Party-backed candidate, of which there were four.
But Young beat out state Rep. Chad Fincher' newspaper columnist Quin Hillyer, who was endorsed by Rick Santorum; and former Republican National Committee aide Wells Griffith, who was backed by Rep. Paul Ryan (R-Wis.), for the second-place spot.
Whichever Republican wins in the Nov. 5 primary runoff will face Democrat Burton LeFlore on Dec. 17 and is expected to easily win the seat.
Byrne, Young advance to runoff in Alabama 1st District special election
No candidate in the nine-candidate field was on track to take more than 50 percent of the vote, but with about sixty percent of precincts reporting, The Associated Press called the runoff in the race to replace retired Rep. Jo Bonner (R).