Bell, who inherited the lead by staying out between Stages 2 and 3, led the final 100 laps but had to ward off repeated challenges, with the last coming from Reddick in the final five laps.
Reddick, who won Stage 2, pitted for new tyres during the break and put them to good use to challenge for the win .
On lap 224 of the 250-lap encounter, Reddick went to the inside of Chase Briscoe and moved into the second position to begin his hunt down of Bell.
The fight for victory was briefly suspended by a caution period, after Kyle Busch reported a mechanical problem with his #8 Chevrolet that later resulted in him spinning off at Turn 4 and down towards pitroad on lap 235.
The race resumed with eight laps remaining, with Bell in front followed by Reddick, Ryan Blaney, Austin Dillon and Briscoe.
With Reddick closing in for a final attempt at a pass on the last lap, he was denied by the 14th and final caution period of the race, for the stopped car of Ross Chastain at Turn 4, which secured the win for Bell.
Bell’s first triumph of the season also sees him leap to the top of the drivers’ standings – coupled with Chastain’s late dropout – and continues a remarkable start to the 2023 season for the 28-year-old, who has five top-five finishes in the first eight races of the campaign.
Race winner Christopher Bell, Joe Gibbs Racing, Toyota Camry
Photo by: John Harrelson / NKP / Motorsport Images
“These are some of the longest laps of my entire life. This place is so much fun, whether it is dirt or concrete,” Bell said. “Whenever the cushion got up there on the top [lane], it was very tough because you couldn’t drive it super hard otherwise you’d get sucked in.
“If you got your right-front into it, you’d push a little bit. If you got your right-rear into it, you’d slide. It was a lot of fun.”
Several times in the last 25 laps, Bell looked like he may slam the wall in Turns 3 and 4, which he called “the scary corner”.
“If you got into it too far, you lost all your momentum. [Turns] 1 and 2, I think I kept hitting the wall a couple times. Seems like there was a little bit more moisture up there, it would hold me better.
“I am like, ‘Okay, I can really attack [Turns] 1 and 2.’ But 3 and 4 I had to be careful.”
With Reddick having to settle for second it did keep him clear of Dillon who claimed his best finish of the season, ahead of Daytona 500 winner Ricky Stenhouse Jr, with Briscoe also taking his best result of the year in fifth.
Another new best result of the season came for Justin Healey with sixth, ahead of Martin Truex Jr and Todd Gilliland, as Kevin Harvick and Ty Gibbs completed the top 10.
After winning the opening stage, Kyle Larson clashed with Ryan Preece, with the Stewart-Haas driver hitting the wall and falling to the back of the pack, while early in the third stage Larson spun to drop him to 35th at the finish.
NASCAR Cup Bristol dirt – Race Results