Johnson took the lead just before the race's final caution then fended off Hendrick Motorsports teammate Earnhardt to eke out a 0.129-second margin of victory.
Johnson, who previously took NASCAR's signature season-opening event in 2006, became the 10th driver to win the event at least twice.
Ryan Newman rounded out the Top 5.
Pole-sitter Danica Patrick finished eighth -- the highest-ever placing by a female driver at the Daytona 500.
Kuchar downs Mahan for Match Play title
Kuchar was never headed during the championship match, and trailed for a total of only five holes during the entire five-day event at The Golf Club at Dove Mountain.
The win was his first World Golf Championship title and his fifth PGA Tour victory overall.
Mahan's streak of 169 holes without trailing at the match play event was broken on the fourth hole of Sunday's title round.
Jason Day took the consolation match with a 1-up decision over Ian Poulter.
PGA Tour won't ban putter anchoring
MARANA, Ariz., Feb. 24 (UPI) -- The PGA Tour won't follow the R&A and USGA in banning the anchoring of putters, Commissioner Tim Finchem announced Sunday.
Finchem said such a ban wouldn't serve the pro tour well.
While the other golf organizations didn't prohibit the use of long putters or belly putters outright, they did ban the "act of anchoring any club against a player's body during a shot" in November.
"Where the PGA Tour came down was that they did not think banning anchoring was in the best of interests of golf or the PGA Tour," Finchem said.
"I would note that the PGA of America came to the same conclusion after consultation with their membership," he added. "(The) Golf Course Owners Association came to the same conclusion as well."
The decision won't set up a dispute between the PGA Tour the USGA, he said.
Yanks' Granderson out with arm fracture
TAMPA, Fla., Feb. 24 (UPI) -- New York Yankees outfielder Curtis Granderson broke his right forearm when hit by a pitch Sunday in a spring training game and will be out 10 weeks.
Granderson was taking his first at-bat of the preseason when he was drilled on the forearm by Toronto Blue Jays pitcher J.A. Happ.
Initially diagnosed with a bruise, the outfielder was found to have suffered a fracture after being taken to a local hospital for X-rays.