"Rees-Lightning has arrived," the Chiefs posted on X with a lightning bolt emoji and a photo of the 23-year-old Welshman playing for his homeland in a "Chiefs Kingdom" welcome.
"Hi Chiefs Kingdom. Louis Rees-Zammit here. Just signed. Can't wait to go and see you all at Arrowhead (Stadium)," Rees-Zammit said in a video clip posted on X.
The NFL Network reported that Rees-Zammit, who played for English Premiership side Gloucester from 2018 until this year, has signed a three-year deal with a signing bonus and some portion of the deal guaranteed. That's a crucial part of the deal with NFL teams able to end contracts by dropping players.
Rees-Zammit said in January he was leaving rugby union to explore an NFL career and became part of the NFL International Player Pathway Program, created in 2017 to help global athletes make their way into American football.
Rees-Zammit conducted a workout for scouts last week - one the Chiefs said included a 4.44-second 40-yard dash that would have ranked fifth among tailbacks at this year's NFL Scouting Combine for NFL Draft talent.
The Welshman reportedly visited the New York Jets, Cleveland Browns and Denver Broncos as well as the Chiefs before settling on a desired new NFL home.
He becomes the 37th player from the global talent program to sign an NFL contract and now hopes to become only the sixth to reach an active roster spot. NFL clubs receive a training camp roster exemption for an international player and this year have a practice squad global berth available specifically for such a player as Rees-Zammit.
NFL teams are allowed to elevate international players from the practice squad three times during the season, providing more chances for players to develop and improve by facing top-level opponents in regular-season contests.
There's also a chance Rees-Zammit, being eyed as a rusher or wide receiver as well as on kick teams, could make the main roster depending on how well he performs in Chiefs training camp workouts and pre-season games.
But it's a rare feat, thus far only achieved by Philadelphia offensive tackle Jordan Mailata of Australia, a former rugby league player; Washington defensive end Efe Obada, a Nigerian-born Briton; German fullback Jakob Johnson of the Las Vegas Raiders plus former Washington defensive lineman David Bada of Germany and former Washington tight end Sammis Reyes of Chile.
Rees-Zammit, in a posting on the Chiefs website, said his favorite NFL player when he was a child was wide receiver DeSean Jackson, who played five seasons in Philadelphia under current Chiefs coach Andy Reid.
Rees-Zammit might also be aided in his NFL dream by rule changes approved by NFL club owners this week regarding kickoffs, which were converted to a more rugby-style catching and runback format with kicks from well behind a spread-out line - only Rees-Zammit would have the aid of blockers on kick returns.
