Pratt, who scored 25 tries from the wing this year, is seen as a high- class stand-off for the future. He was pursued by several other Super League clubs, notably Wigan.
For Leeds, the sliding scale fee of up to pounds 150,000 that they will eventually pay Featherstone will be an expensive way of redressing a mistake made three years ago. Pratt, a local lad, was training at Headingley, but was allowed to slip away.
He returned to his amateur club at Hunslet Parkside, joining Featherstone two seasons ago and making an almost immediate impact.
"My two years at Post Office Road have been an invaluable learning curve, but my ambitions have to be centred on Super League," Pratt said as he signed at Headingley yesterday.
"The Rhinos are my hometown club and are geared up for success on and off the field."
Pratt, a current Great Britain Academy international, will make his debut on Boxing Day against Halifax, along with their other new signing, Lee Jackson, and Wendell Sailor, who is here primarily to play rugby union for Leeds Tykes.
Graham Murray, the Leeds coach, said: "There is the continued need to look forward and Karl joins us as the hottest young property in the British game, with a flair for try-scoring."
The Featherstone chairman, Richard Evans, tried to put a brave face on the loss. "Karl Pratt is a player of exceptional ability for one so young and his move to a higher level was indeed inevitable and unavoidable," he said.
"While we are obviously saddened to lose such a talented player, it would have been unfair to have stood in the way of his progress.
"In an epic Grand Final, the club was a mere five minutes away from Super League status. Had Rovers won then things would have been very different and Karl would have been more than happy to move up with us.
"Our fans need not be despondent, as the considerable compensation fee will help pave the way for the emergence of a very strong and committed Featherstone Rovers, totally undeterred in our quest to achieve Super League status at the very earliest opportunity."
As if to back up those sentiments, Featherstone have quickly made two signings with the proceeds from Pratt - the Dewsbury full-back, Matt Bramald, and the New Zealander, Hitro Okesene, an experienced prop who has played in Super League with Hull.Reuse content