Sebastian Coe has hailed the Paralympic Games as "a triumph of human endeavour".
In a foreword published before the closing ceremony, Lord Coe said spectators were "moved, dazzled and inspired" by the sporting successes of the past 11 days.
He said: "As we join the world for a grand global goodbye to the Paralympic athletes, teams and sports officials at this evening's Closing Ceremony, I would like to thank everyone who has been a
part of this historic odyssey of human achievement and endeavour.
"We were moved, dazzled and inspired by Paralympic athletes who refused to say 'no', and provided sporting performances of stunning imagination, creativity, courage and determination.
"The Paralympic athletes showed what is possible - that sport is about what you can do, what you can overcome, the barriers and attitudes you can break, that the human spirit is stronger than steel
and far more resilient than many thought possible."
The London 2012 chairman thanked everyone who helped the Games to run smoothly.
"Most importantly, this was a journey of inspiration for everyone, especially young people, and I would like to thank the millions of people across the country and around the world, people of all
ages and from all cultures and backgrounds - from scientists and Shakespearean actors, to teachers, nurses, bus drivers, the men and women in uniform, and especially our much-admitted Games Maker
volunteers, coaches, parents and sport club volunteers and many, many others from all walks of life and all levels of ability - who made this journey possible for us and the athletes.
"You have made these Games a triumph of human endeavour and international collaboration and helped make a statement about why sport matters so much as a catalyst for hope and change in difficult
and challenging times. You have inspired a generation and made London 2012 a very special time in the lives of people everywhere."
President of the International Paralympic Committee Sir Philip Craven said that the sporting event had made the world "a more equitable place".
"For all athletes competing here on the world stage, in front of billions, these Games have been the opportunity of a lifetime," he said.
"Their performances have delivered something far more tangible than medals. They have ensured that the world is a more equitable place than it was 12 days ago."
The Earl of Wessex acknowledged both the athletes and all the volunteers who helped to run the Games.
"The closing ceremony of the London 2012 Paralympic Games gives us a chance to reflect on a most extraordinary festival of sport and celebration.
"This evening we particularly recognise the endeavours and achievements of Paralympians. Once again they've shown a spirit of sportsmanship which frankly leaves most of us feeling pretty humble yet
at the same time uplifted."
He paid tribute to "the countless volunteers" who have worked at the event.
"While some of us celebrate a huge success and enjoy the festivities, there will be others for whom this event will evoke very strong and mixed emotions of joy, relief and not a little sadness as
new-found friends disperse to their homes."
Prime Minister David Cameron said: "The inspirational power of Paralympic athletes has shown us what can be achieved, and proved that records are there to be broken. Rather than be constrained by
what some see as limits, these athletes have excelled, and in doing so helped change attitudes to disability forever.
"I am delighted with that success, and the positive impact on society, just as I have been thrilled with the quality of the sport we have all seen.
"This has been a summer of brilliant achievements that will never be forgotten, and lives will be transformed as a result."
Mayor of London Boris Johnson said he was proud that the capital had hosted the Paralympics.
"Britain has always cherished its Paralympic heritage, from the birth of the movement on these shores 64 years ago to the outstanding performances of our Paralympic team at recent Games.
"But this year, our capital has finally earned the title of Paralympic Host City, and no Londoner is more proud of that than me."
And he pledged that more would be done to make the capital as accessible as possible for people with disabilities.
"We are not complacent: despite our achievements, there are more barriers to overcome before life in London is as inclusive and accessible as we would like it to be.
"Inspired by the Paralympic Games, we embark on the next stage of that journey today with a determination that would make any Paralympian proud."