Teams have an off-season training squad of 90 players and must select 53 for the start of the season, the deadline for which was Tuesday.
He was placed on waivers meaning other teams could sign him, though it had been expected he would continue his development in Kansas having initially signed a three-year contract with the Chiefs.
Jacksonville were one of several franchises that showed interest in Rees-Zammit after his impressive showing in the IPP pro day in March.
The forrmer British and Irish Lion made his American Football debut against Jacksonville earlier this month in Kansas City’s opening pre-season game.
Each NFL team can have one player who was signed through the IPP program on its practice squad alongside 16 other players.
Practice squad players can work out during the week with NFL teams but are ineligible to play in actual games unless the player is elevated to the regular roster.
Rees-Zammit shocked the rugby world in January when he announced he was quitting Wales and Gloucester to pursue a dream to play in the NFL.
He will now pursue that ambition with Jaguars in Florida according to a source reported by ESPN, external.
The Jaguars franchise have a strong presence in the UK. They will play twice in London this season, facing Chicago Bears at Tottenham Hotspur Stadium before hosting the New England Patriots at Wembley.
The New York Giants have "mutually agreed" to terminate the contract of quarterback Daniel Jones, less than two years after he signed a $160m extension with the
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