Reid, 61, won a Super Bowl ring with the 1996 Green Bay Packers while in charge of tight ends. He's been seeking one as a head coach since being hired by Philadelphia in 1999. The Eagles lost in their only trip to the big game under Reid after the 2004 season.

"This is what it's all about," Reid said as confetti fell and the Chiefs celebrated the climax of the NFL's 100th season. "What a great team, great coaches. Appreciate every bit of it."

Mahomes found Hill, whose bobble led to the second San Francisco pick, for 44 yards on a third-and-15-the first long pass completed by Kansas City. A 20-yard pass interference call on Tarvarius Moore, who had that earlier pick, put the ball at the 1 and Kelce was wide open for the score.

The Chiefs defense, confounded by the Niners' misdirection much of the game, got stingy and forced a threeand-out. Mahomes soon hit Watkins down the right sideline behind Richard Sherman for a 38-yard gain, leading to Williams' first score.

San Francisco (15-4) had nothing left in the fourth quarter, and its coach, Kyle Shanahan, saw yet another late-game meltdown by his team. Three years ago, as offensive coordinator in Atlanta, he was part of the Falcons' Super Bowl collapse and loss in overtime to New England.

"We'll lick our wounds and we'll get over this," Shanahan said.

Kansas City, an original AFL franchise, won the final Super Bowl before the full merger, beating Minnesota in 1970. Chiefs owner Lamar Hunt even coined the phrase Super Bowl.

Now the Hunt family can add a Vince Lombardi Trophy to the Lamar Hunt Trophy earned with the AFC crown.

"It's a beautiful trophy," Chiefs owner Clark Hunt said. "I'm so happy for our players, coaches and fans. And especially Andy Reid. Nobody deserves this trophy more than Andy Reid."