Throughout the season, Reddick has come desperately close to his maiden win, only to see his shot at victory lane vanish.
Last weekend, fortunes changed for the 26-year-old who passed the current drivers' championship leader Chase Elliott in an enthralling race in Plymouth, Wisconsin.
The duo battled for the lead for several laps before the Richard Childress Racing driver muscled around his rival with just 16 laps remaining.
Reddick never lost his lead from that point on, and steadily built his advantage in the closing stages of the race.
After soaking in his victory, Reddick told NBC: "I knew he was fast but we could stay with him on the long run which told me if we cycled through that last pit sequence, we could get close, could get around him and have a great shot.
"I didn't quite get around him. We were within reach. Thankfully, just waited for the right opportunity and was able to take advantage of it in turn six."
This was Reddick's first win in the series following 10 career top-five finishes. As a result, he has now stamped his name onto the play-off list.
"We had to [get it done]," added the Reddick. "What better place than Road America. I love the fans, I love this race track. Being here for the 4th of July weekend is just so special. We got it done. We won the race.
"I made a lot of mistakes along the way, but this year has been one mistake away from greatness all year long. We finally did it today, it feels good."
Elliott held out for a second-placed finish, which marked his third podium of the 2022 season.
Kyle Larson finished third, while Kyle Larson and Daniel Suarez rounded-off the top five.