A full-length portrait features the Queen accompanied by the Duke of Edinburgh, who wears his military uniform, medals and honours, while a second photograph has the Queen on her own.
Both were taken in December in Buckingham Palace’s famous centre room, used by the Royal Family to reach the balcony overlooking The Mall.
As the Queen reached the milestone of 60 years on the throne, she issued a heartfelt message renewing her pledge to serve the nation and its people.
“In this special year, as I dedicate myself anew to your service, I hope that we will all be reminded of the power of togetherness and the convening strength of family, friendship and good neighbourliness,” she said.
The words echo her famous commitment on her 21st birthday, when she vowed: “I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family to which we all belong.”
The 85-year-old monarch thanked all those who had given “wonderful support and encouragement” to her and the Duke of Edinburgh over the past six decades.
And she said she and Prince Philip had been “deeply moved” by the many kind messages they had received about her 60-year milestone.
The two new photographs were taken by John Swannell, who has photographed many members of the monarchy, including the sovereign to celebrate her golden jubilee in 2002.
He said: “This is the third time I’ve had the pleasure of photographing Her Majesty, and I always find these events very exciting.”
He said it was an “intricate” shoot that he had to set up the day before.
“The Queen and Prince Philip, I thought, were patient and very relaxed on the day, which I hope is reflected in the photographs.”
In the images, the Queen is wearing a state dress of white silk, satin and lace with silver coloured sequins. It has a flowing scalloped edge, and was created by her dresser and personal assistant, Angela Kelly.
On her head is the State Diadem, a circlet of 1,333 diamonds, created in 1820 for George IV and worn by the monarch for the state opening of Parliament.
The Queen is also wearing Queen Victoria’s Collet necklace, which has graced the necks of five generations of royal women – Victoria, Queen Alexandra, Queen Mary, the Queen Mother and the present sovereign.
Prime Minister David Cameron said the UK should use the 60th anniversary of the Queen’s accession to the throne to thank her for guiding the nation with “dignity and quiet authority”.
Some people characterised the monarchy as simply “a glittering ornament, a decoration on our national life”, he noted.
“That misunderstands our constitution and it underestimates our Queen. Always dedicated, always resolute and always respected, she is a source of wisdom and continuity.
“All my life, and for the lives of most people in this country, she has always been there for us. Today, and this year in the 60th anniversary of her reign, we have the chance to say thank you.”
• Web users can find out the latest information about the Queen’s diamond jubilee from a website launched today.
It will feature up-to-date news, photographs and announcements about the jubilee. Among its web pages, at thediamondjubilee.org, will be historical information about the sovereign’s six decades of service.
Visitors can search an events map to find royal engagements and send a congratulatory message to the monarch.