Mackey crossed under the famed burled arch in downtown Nome early Tuesday evening, completing the 1,100-mile Iditarod in just over nine days.
He celebrated as he came down Nome's Front Street, alternately waving a fist in the air, then high-fiving fans that lined the street. His family mobbed him at the finish line.
"Dreams do come true, Mama, they do" Mackey said after the race, fighting back tears.
"This is my passion," he told reporters, adding he was proud to follow in his father's footsteps and joked about being thankful his father was a musher and not a lawyer.
"It's our lifestyle, it's what we breathe, eat and sleep," he said of the Mackey family's love of mushing. "It's what we do."
On Feb. 20, Mackey won his third consecutive Yukon Quest International Sled Dog Race, a 1,000 mile race between Fairbanks and Whitehorse, Yukon.
With only 12 days rest, Mackey took 13 of his 16 dogs from the Yukon Quest to Willow for the March 4 official start of the Iditarod. In the two races, the dog team covered a distance equivalent to mushing from Boston to Salt Lake City.
Mackey, 36, joins his father, Dick, and brother, Rick, as Iditarod champions. Both won the race wearing bib No. 13 and each the sixth time they ran the Iditarod. Lance Mackey camped out for days at the Iditarod headquarters last June to be the first person to sign up for this year's race in order to select the No. 13 bib.
This was also his sixth time in the race.
Many mushers have long believed it would not be possible to win both races in the same year with the same dogs because the animals would need more time to recover from one grueling race before launching off on another.
Mackey's win proves that is not so.
Canadian Hans Gatt, 49, a three-time Quest winner who was also runner-up to Mackey twice, said Mackey's team was the best-looking team on the Iditarod trail this year. Instead of tiring, his team recovered faster than any of the others after long runs between checkpoints and maintained their speed.
"I can't run my dogs like that," Gatt, of Whitehorse, said Tuesday, almost 100 miles back on the trail. "He obviously has figured out something we have not figured out yet."
Mackey was the first musher early Tuesday morning to the White Mountain checkpoint, about 80 miles from the finish line and where mushers must take a mandatory eight-hour rest. He built a two-and-a-half hour lead over the second musher into White Mountain, Paul Gebhardt, 50, of Kasilof.
Sled dog racing is a sport where mushers perform more for glory than big-time payouts, having to rely heavily on sponsorships to continue feeding their dogs.
For winning the world's longest sled-dog race, Mackey will pocket $69,000 and be handed the keys to a $41,000 pickup.
Mackey has been thinking about that truck along the trail and for good reason. One year, when he was trying to get to the start of the Quest, he was fined $500 for missing a meeting for mushers. The reason he was late was that the two trucks he was driving broke down. One lost an engine and the transmission went out in the other.
Just before this year's race, he splurged on a used, 14-year-old pickup.
Mackey, who has named his kennel Lance Mackey's Comeback Kennel, was diagnosed with neck cancer in 2001 and underwent surgery and radiation.
With a feeding tube into his stomach and still undergoing cancer treatment, Mackey started the 2002 Iditarod but was forced to scratch in Ophir more than 400 miles from Anchorage. Mackey now is cancer-free. Mackey's father, Dick Mackey, is considered one of the founders of the race, which began in 1973. Dick Mackey won in 1978. His brother, Rick, became champion in 1983.
This year's Iditarod has been marked by poor trail conditions, causing an inordinate numbers of mushers — 21 — to scratch. One musher also took a wrong trail, prompting a search, and one dog died during the race.