In just two seasons as a starter, Kansas City Chiefs quarterback Patrick Mahomes already owns NFL and Super Bowl MVP awards.


Now the young superstar appears on the brink of becoming owner of something even more impressive — the richest contract in NFL history.


The world-champion Chiefs have reached an extension with Mahomes that will keep the former Texas Tech gunslinger in Kansas City long-term, the franchise announced Monday night.


The Chiefs didn’t immediately disclose the terms of the agreement, though Steinberg Sports, the agency that represents Mahomes, revealed it as a 10-year extension worth $503 million. Of that sum, $477 is in guaranteed mechanisms, according to the agency.


"First half billion dollar player in sports history," the agency tweeted. "History made."


General manager Brett Veach said getting a deal done with Mahomes has been "a priority ... for quite a while now."


"I’ve said from the beginning that Patrick is one of the most impressive players I’ve ever scouted, but I don’t think anyone could have envisioned everything he’s brought to our football team and community," Veach said in a news release. "His abilities are so rare, and to couple that with an incredible personality is outstanding. We’re going to continue to do everything we can to surround him with talent, and this deal provides us more flexibility to do that. He’s obviously an integral part to our success and we’re thrilled he’s going to be the quarterback of the Kansas City Chiefs for a long time."


Mahomes had two years worth $27.6 million remaining on his existing contract, making his new agreement a 12-year deal that will keep the quarterback in Kansas City through the 2031 season.


"I’ve had the privilege of coaching a lot of incredible athletes and special people in my career, and Patrick is without question on that list of players," said head coach Andy Reid. "The best part is he’s still early in his career. He’s a natural leader and always grinding, whether that’s on the field, in the weight room or watching film, he wants to be the best. He’s a competitor and his teammates feed off his energy. He makes us all better as an organization and we are blessed he’s going to be our quarterback for years to come."


Chiefs chairman and CEO Clark Hunt labeled the extension a "significant moment for (the) franchise."


"Since he joined the Chiefs just a few years ago, Patrick has developed into one of the most prolific athletes in all of sports," Hunt said. "With his dynamic play and infectious personality, he is one of the most recognized and beloved figures to put on the Chiefs uniform. He’s an extraordinary leader and a credit to the Kansas City community, and I’m delighted that he will be a member of the Chiefs for many years to come."


Since replacing Alex Smith as the Chiefs’ starter in 2018, Mahomes has thrown for 10,602 yards and 89 touchdowns. He also has led KC to 27 wins — including a 31-20 victory against the San Francisco 49ers in the Super Bowl earlier this year — with a quarterback rating of 79 and 8.5 yards passing per attempt.


All of those statistics are league-leading figures.


Mahomes, 24, is the first quarterback in NFL history to win both league and Super Bowl MVP awards before turning 25, displaying a knack for rallying the Chiefs to dramatic victories.


The Chiefs drafted Mahomes in 2017, trading up to get the Texas Tech standout with the 10th overall selection.