Blaney led a race-best 63 of the 191 laps in the GEICO 500, which was pushed back one day because of inclement weather Sunday at the central Alabama track. Poor weather also impacted Monday's event, as storms in the area forced a delay that lasted about one hour with 57 laps complete.
Blaney's second consecutive win at the 2.66-mile track was the fourth of his Cup Series career.
"Really excited to get our first win of the year at a cool place," Blaney said. "That was a lot of fun."
Stenhouse squeezed by Aric Almirola for second place, finishing only .007 seconds back from Blaney at the checkered flag. Almirola came in third, followed by Denny Hamlin (fourth) and Erik Jones (fifth).
Prior to the race, fellow NASCAR drivers and crew members showed their support for Bubba Wallace, who was the target of a racist incident Sunday in the garage area.
The Federal Bureau of Investigation and other federal authorities launched an investigation after a noose was found in Wallace's garage.
In response to the incident, drivers and pit crew personnel stood beside Wallace during the national anthem and then pushed his No. 43 Chevrolet to the front of the grid before the Cup Series race.
Wallace, who is the only black driver in the Cup Series, ran as high as third in the final 20 laps before dropping to 14th because of a fuel shortage.
"The sport is changing. The deal that happened yesterday, I just wanted to show whoever it was that you're not going to take away my smile," Wallace said after the race. "I'm going to keep on going. ... The pre-race deal was probably one of the hardest things I've ever had to witness in my life.
"From all the supporters, from drivers, from crew members, everybody here ... It was truly incredible and I'm proud to be a part of this sport."
Chris Buescher (sixth), Alex Bowman (seventh), John Hunter Nemechek (eighth), Kurt Busch (ninth) and Kevin Harvick (10th) rounded out the top 10. Jimmie Johnson finished 13th and Joey Logano ended up in 17th.
The crowd at Talladega dwindled significantly from Sunday, when up to 5,000 fans were allowed into the track. It was the second race with fans since NASCAR returned from its pandemic-related shutdown.
The NASCAR Cup Series' next race weekend features a doubleheader, with events scheduled Saturday and Sunday at Pocono Raceway in Long Pond, Pa.