HRH the Duke of Cambridge and former England captain Beckham helped to launch a 12-month celebration of English football at the Grand Connaught Rooms in Holborn.
The FA President and Beckham contributed messages of support in front of a star-studded audience, including five England managers and a host of World Cup winners.
The FA's 150th anniversary year will see football's oldest governing body recognising the 400,000 volunteers, 300,000 coaches and 27,000 referees who offer their time to the sport in this country.
Prince William said: "I would like it to highlight the incredible efforts of the 400,000 volunteers that deliver the game week in, week out, up and down the country. The mums and dads, coaches, referees and administrators who give their time to make pitches ready, organise the fixtures and wash all those kits.
"The Olympics and Paralympics highlighted the spirit of the British people to volunteer, but I know it is something that has always been part of our great game.
"I am delighted that The FA will be honouring this army of volunteers through a special 150 Grassroots Heroes initiative. They deserve our full praise and unstinting thanks."
Beckham reflected on his early participation in the grassroots game before describing his pride at captaining the national team.
"Football has been a huge part of my life from a very young age," he said.
"My early memories are getting up early on a Sunday morning with my mum and dad, both of them taking me to Sunday morning football with, first off, Ridgeway Rovers, then Brimsdown and then up to Manchester every single weekend.
"When I speak about playing for Manchester United, I speak about how proud I am to have achieved what I have achieved.
"When we speak about playing for England and wearing the Three Lions shirt in front of a full house at Wembley; it's the proudest moment an English person can have, stepping out not just as an England player, but stepping out as captain of your country.
"For me, it's the proudest moment that I have had in my career."