The Chiefs were looking to become the first NFL team since the New England Patriots in 2003 and 2004 to win back-to-back Super Bowls.
But Mahomes and the Chiefs were overpowered by a brutal Buccaneers team – spearheaded by superstar quarterback Brady and a relentless defensive and offensive line in Tampa on Sunday.
Mahomes and the Chiefs were stifled by the Buccaneers, who claimed their first Lombardi Trophy since the 2002 season as Brady clinched a record-extending seventh championship ring.
After finishing 26-of-49 passing for 270 yards, no touchdowns, two interceptions and three sacks, Mahomes told reporters: "The worst I've been beaten in a long time, but I'm proud of the guys and how they fought until the end of the game."
"We weren't on the same page as an offense in general," Mahomes said. "I wasn't getting the ball out on time, receivers were running routs not exactly where I thought they'd be.
"The offensive line, they were good at times but sometimes let guys through. When you play a good defense like that, you have to be on the same page as an offense and we weren't. That's why we played so bad."
Mahomes had little support as he was roughened up by the Buccaneers, though the 2018 NFL MVP was far from his best despite a battling performance.
Asked about an ongoing toe problem and whether he requires surgery, Mahomes replied: "I can't say my toe was a problem when I played two weeks ago and played well on it.
"You're playing football, you have to battle through injuries.
"We'll look at it tomorrow [Monday] and make a final decision as to whether to have surgery or not."
There have been eight teams all-time to reach the Super Bowl after averaging at least 410 total yards per game – the Denver Broncos (2013), Miami Dolphins (1984), New England Patriots (2011 and 2007), Los Angeles Rams (2018 and 2001), the Atlanta Falcons (2016) and Chiefs this year. All eight sides went on to lose the showpiece, per Stats Perform.
Despite the comprehensive nature of the defeat, Mahomes was upbeat afterwards.
"My dad lost in the World Series in his [MLB] career and he continues to battle and be who he is," Mahomes added. "Obviously it hurts now, it hurts a lot. But we are going to continue to get better. We have a young group of guys that have had a lot of success and learnt from that, but a few failures and we have to learn from that.
"We can't let this define us. We have to get better, going into next year, being even better in preparing ourselves to hopefully be back in this game next season."
He continued: "We have a young group of guys, when we joined together we knew it wasn’t always going to be successful and you weren't going to be able to win 1,000 championships in a row.
"We knew we would go through times like this and adversity. Leadership ability to be better next year. Obviously we didn't end the same the way we wanted to but we can learn from that and learn from successes through the season, end of the day come in at blank slate and get to the Super Bowl again."