The event was attended by staff, supporters, partners and beneficiaries - including front-line ophthalmologists and eye health professionals from across the Commonwealth - to celebrate the Trust's achievements.
Sophie took to the stand and paid tribute to the Queen in her speech, praising her "mama" as she said the charity had ensured the Queen would leave a lasting legacy.
Speaking in front of the 200 attendees - all of whom the queen met personally - Sophie said: "I feel in a way that I have been your eyes, having travelled to Malawi, Bangladesh and India to see the work of the Trust first-hand, witnessing the ambitious initiatives being carried out in Your Majesty's name, and ensuring that the intended legacy would be real and long lasting.
"I am very happy to say that Your Majesty's honour has been more than upheld," she said.
Sophie highlighted the exceptional work of the Trust over the years.
"The Trust has concentrated on tackling curable eye diseases, including diabetic retinopathy, retinopathy of prematurity and a particularly widespread and painful eye issue, blinding trachoma.
"This ancient disease, which even warrants a mention in the Bible, has been one of the most prevalent and out of control eye conditions the world has known and now, across the Commonwealth and beyond it is on the run."
Sophie continued: "Mama, when I have returned from my travels I have been so proud to share with you the work I have witnessed being carried out under the umbrella of the Queen Elizabeth Diamond Jubilee Trust and the care of so many people working so hard to save and cure sight.
"Each time you have listened with interest and been eager to hear of how the work is going, and each time I have been stunned as you have shared with me your deep knowledge of each of these countries, not top level observations, but personal experience, demonstrating to me time and again the real affection you have for all people of the Commonwealth and why that affection is so abundantly returned by them to you."
Continuing her praise, Sophie added: "On your 21st Birthday, while on a tour to South Africa you made a promise to dedicate your life to the service of the Commonwealth.
"You have carried out this promise in so many ways ever since, but your Diamond Jubilee Trust has I believe allowed Your Majesty to demonstrate your dedication in a tangible and practical way, which has and is enriching the lives of people across the Commonwealth and will be felt by generations to come," she said.
Since 2014, the Trust has helped more than 22 million people in Africa and the Pacific receive vital antibiotics to combat trachoma - the world’s leading infectious cause of blindness and provided sight-saving surgery to over 104,000 people suffering with trachoma trichiasis.
Sophie's close relationship with Queen Elizabeth stems from the fact the Queen find's her presence soothing.
A royal insider told The Sun: “The Queen likes to be completely calm before church and she finds Sophie’s presence soothing.”
They added: “She is trusted and relied on by the Queen in a way I couldn’t say applied to the Duchess of Cambridge or the Duchess of Cornwall.
“She is like another daughter to Her Majesty, they are that close.”