Byron, 23, had to work his way to the front after starting 31st but once he got there, it was difficult to dislodge him.
Byron led a race-high 102 of 267 laps and easily held off Tyler Reddick by 2.8 seconds to win Sunday’s Dixie Vodka 400. Byron led the final 58 laps.
The win is just the second of Byron’s Cup career and first coming with crew chief Rudy Fugle, with whom Byron had enjoyed much success in the Truck Series.
“I mean that guy has been huge for my career; he’s the reason I’m here,” Byron said of Fugle. “I’m glad we could get him. He’s just awesome.
“This whole team did a phenomenal job – everybody pit crew, over-the-wall. I’m extremely blessed. I can’t believe it, honestly. It was just a really smooth day. We worked hard over the winter on this track and I just can’t believe it.
“You had to go to the wall at certain times – (Turns) 3 and 4 were really fast up there. I definitely didn’t do it as often as the Xfinity cars did it but I used it when I had to. This car was just awesome.”
Byron becomes just the eighth driver in Cup Series history with multiple wins before turning 24 years old. The others – Kyle Busch (14), Jeff Gordon (seven), Chase Elliott (six), Richard Petty (five), Joey Logano (five), Junior Johnson (four) and Erik Jones (two).
Martin Truex Jr. ended up third, Kyle Larson fourth and Kevin Harvick rounded out the top-five.
Completing the top-10 were Michael McDowell – who sits fourth in points after three races; Ryan Newman; Kurt Busch, Alex Bowman; and Kyle Busch.
Following the break between Stages 2 and 3, most of the lead-lap cars elected to stay on the track, including Byron who remained the leader.
On the restart on Lap 168, Byron was followed by Denny Hamlin, Kurt Busch, Larson and Chris Buescher. Truex, the first among those who pit, restarted 17th.
On his new tires, Truex worked his way to fourth two laps following the restart as Byron continued to lead.
With 70 laps to go in the race, Byron held a 1.2-second lead over Truex with Larson third, and Hamlin fourth.
On Lap 200, Aric Almirola went up the track and failed to clear Ryan Blaney with both getting into the wall in Turn 3.
All the lead-lap cars pit with Larson the first off pit road followed by Truex, Hamlin, Kurt Busch and Harvick. Hamlin was forced to restart from the rear of the field after speeding on pit road during his stop.
The race returned to green on Lap 208. Hamlin restarted 28th.
Truex quickly grabbed the lead on the restart but Byron began challenging again for the top spot and returned the lead on Lap 210.
With 40 laps remaining in the race, Byron had built a 2.2-second lead over Larson followed by Truex, Kurt Busch and Cole Custer.
On Lap 229, Kurt Busch was forced to pit under green for a vibration, which turned out to be a left-front loose wheel.
With 30 laps to go, some drivers decided to pit under green for tires, including Keselowski and Logano, who both had fallen out of contention for the win after running up front early in the race.
With 15 laps remaining in the race, Byron’s lead had ballooned to 4.6 seconds over Larson. Truex remained in third, Harvick fourth and Reddick moved up to fifth.
Byron went from third to first in a one-lap dash and held off Hamlin to win Stage 2.
Truex was third, Kurt Busch fourth and Larson rounded out the top-five.
Following the break between Stages 1 and 2, all lead-lap cars decided to pit with Buescher once again the first off pit road.
When the race returned to green on Lap 88, Buescher was followed by Brad Keselowski, Bowman and Chase Elliott.
On Lap 89, Elliott went to the inside of Buescher and came away with the lead for the first time in the race.
Four laps later, Buescher reclaimed the top spot with Elliott second and Larson in third.
Larson passed Elliott on Lap 99 to take over the second spot as Byron moved into third.
With 50 laps to go in the second stage, Buescher had a 1.7-second lead over Truex as Larson dropped to third.
Some drivers hit pit road on Lap 118 to begin a round of green-flag pit stops for tires and fuel to make it to the end of the stage. Truex briefly took the lead and then made his stop on Lap 122.
Once the cycle of stops was completed on Lap 125, Truex led the way followed by Buescher, Byron and Austin Dillon.
With 25 laps to go in the stage, Truex had built up a more than 2-second lead over Buescher, followed by Byron and Kurt Busch.
With 10 laps remaining, Truex’s lead remained steady at 1.8 seconds over Buescher and Byron was third, 4.6-seconds behind the leader.
On Lap 154, Corey LaJoie lost the engine on his No. 7 Chevrolet, which brought out a caution. The lead-lap cars all pit with Truex the first off pit road followed by Hamlin, Kurt Busch and Byron.
The race returned to green with one lap to go in the stage.
Buescher passed Keselowski with one lap remaining and held on to take the Stage 1 win, just the second stage victory of his career.
“We got a lot of race left to do, but we’ve got a good race car. Even before that caution came out, I was rolling out of it some and trying to take it easy,” Buescher said over his team radio. “We’ll see what we’ve got for them as we get deeper.”
Truex was third, Byron fourth and Bowman rounded out the top-five.
Since Hamlin was forced to star the race from the rear, Logano inherited the pole and easily led the way on the first lap.
On Lap 13, Keselowski made his way around Logano to take the lead for the first time in the race.
With five laps until the competition caution, Keselowski had moved out to a more than 2-second lead over Logano with Kurt Busch in third.
On Lap 26, NASCAR displayed a competition caution to allow teams to check tire wear. All the lead-lap cars elected to pit with Keselowski the first off pit road.
Keselowski led the way on the restart on Lap 30 followed by Kurt Busch, Logano and Harvick.
Halfway through the 80-lap stage, Keselowski maintained a small lead over Logano with Buescher third and Byron fourth.
With 30 to go in the first stage, Keselowski remained out front followed by Buescher, Byron and Logano. Bowman, who started the race in the rear, was up to eighth.
Buescher got around Keselowski on Lap 54 to take the lead for the first time. Byron moved into the second spot on Lap 58.
James Davison appeared to have lost his engine and dropped fluid on the backstretch which brought out a caution on Lap 65. The lead-lap cars all pit with Buescher the first off pit road.
On the restart on Lap 73, Buescher was followed by Keselowski, Logano, Truex and Bowman.
Keselowski quickly grabbed the lead after the restart as Buescher dropped to second and Bowman ran third.
Four drivers had to start the race from the rear of the field – Davison (two inspection failures) and Bowman, LaJoie and Hamlin (all for unapproved adjustments).