Rugby league, whose Challenge Cup final has been played at the national stadium since 1929, is only the second sport to be recognised by Wembley, with the five legends set to appear alongside Bobby Moore, captain of England's 1966 World Cup-winning football team.
The final choice was made by the RFL's board of directors from a shortlist assembled following a public vote and a number of selection panels comprising fans, journalists, coaches, players and MPs, and was announced at Wembley 48 hours before the 2012 final between Leeds and Warrington.
RFL chief executive Nigel Wood said: "The RFL board's view echoed that of the many thousands of people who were involved in the selection process in that the statue needed to be a group representation.
"So many players have contributed to the rich history of the sport and its association with Wembley and the board were keen that that should be reflected in the statue.
"Having Risman, Boston, Ashton, Murphy and Offiah all part of the statue means that every generation of the sport is celebrated."
Wembley Stadium managing director Roger Maslin said: "Wembley Stadium is inextricably linked with rugby league and most specifically the Challenge Cup.
"At Wembley Stadium we constantly strive to inspire memories and the players being honoured today have undoubtedly given their supporters and the wider sporting public as a whole plenty of memories to cherish."
Offiah, best remembered for his stunning length-of-the-field try for Wigan against Leeds in 1994, was shocked to discover he would form part of the statue.
"I couldn't believe it when I heard the news," he said. "I've said from the beginning that I'd be proud to support a rugby league statue at Wembley, no matter whom or what it was. But to know that I will be part of the statue is very special. This sits alongside anything that I achieved in my playing career. I'm immensely proud."