The 31-year-old, who joined the Rhinos in 2007, made his 155th and final appearance for Leeds at Wakefield at the end of July and was due to leave the club this close season after six fantastic seasons at Headingley Carnegie.
Head coach Brian McDermott said: “It is unfortunate for Brent that his time at the club finishes with an injury. He leaves the club with everyone’s best wishes and he is held in deep affection by all at the Rhinos.”
Chief Executive Gary Hetherington added: “I am sure in the years to come, Brent will be regarded as one of the finest overseas players, Leeds has ever had and one of the most exciting and talented full backs to feature in Super League. His record at the Rhinos stands comparison against the very best and we wish him the best of luck for the future. He will always remain welcome at Headingley Carnegie as part of the Rhinos family.”
Webb will be at the Rhinos final home game of the regular Super League season this Friday against Salford City Reds when a special tribute will be shown to remember the heroics of a man known to supporters as Superman.