Leicester's Academy has been awarded category one status by the Football Association's Professional Game Board.
The Foxes' Academy has been placed among the country's elite, as one of only six clubs outside the Premier League to receive the category one seal of approval.
"This has been a project that both the Academy and wider club has been strategically focusing on over the past 15 months, with the overall aim of attaining category one status as part of the combined vision of the club and its owners," said the club's Academy director Jon Rudkin.
"It's a very exciting development for the club and the Academy. It will bring the players some excellent and tough challenges, which will be a significant benefit to them as part of their own development, as well as the long-term benefit of the club."
The 24-year-old has put pen to paper on a two-year deal at Roots Hall and is reunited with manager Phil Brown, whom he played under during the pair's time at Hull.
Brown told Southend's official website: "Will had such a fantastic work-rate and desire to succeed and I remember that extremely well from our time at Hull.
"I'm delighted he has joined the club. He's another player, just like John White, who fits the bill perfectly and I'm looking forward to working with him again."
Atkinson, who made 57 appearances for Bradford during their promotion and Capital One Cup final campaign last season, made just eight first-team appearances at first club Hull.
He had loan spells at Port Vale, Mansfield, Rochdale, Rotherham and Plymouth before joining Bradford, initially on loan, in July 2012.
