The queen, who was married to Philip for 73 years, held audiences Tuesday with two incoming ambassadors to the United Kingdom.
She met with the ambassadors -- Her Excellency Mrs. Ivita Burmistre, ambassador from the Republic of Latvia and Her Excellency Mrs. Sara Affoue Amani, ambassador from the Republic of Côte d'Ivoire -- via video from Windsor Castle.
The audience marked the first time Queen Elizabeth has been seen in public since April 17, when the royal family gathered in Windsor for Prince Philip's funeral.
Just a few days later, on April 21, the queen celebrated her 95th birthday in private, at Windsor Castle. She issued a very personal statement on her birthday, describing a "period of great sadness" for her family.
"I have, on the occasion of my 95th birthday today, received many messages of good wishes, which I very much appreciate," Queen Elizabeth said in the statement. "While as a family we are in a period of great sadness, it has been a comfort to us all to see and to hear the tributes paid to my husband, from those within the United Kingdom, the Commonwealth and around the world."
"My family and I would like to thank you all for the support and kindness shown to us in recent days," she said. "We have been deeply touched, and continue to be reminded that Philip had such an extraordinary impact on countless people throughout his life."
Philip's death at the age of 99, marked the end of an era for the royal institution and a new normal moving forward for Queen Elizabeth and her family.
Philip, whom the queen described as her "strength and stay," was by her side at thousands of royal engagements and overseas tours until his retirement from official royal duties in 2017.
In addition to Queen Elizabeth, other royal family members are also resuming royal duties following their two-week period of mourning.
Prince William and Duchess Kate visited a farm on Tuesday, their second official royal engagement since Philip's funeral.
The Duke and Duchess of Cambridge visited a family-run farm and a local youth project in County Durham.
The youth project visited by William and Kate, called the Cheesy Waffles Project, is supported by one of the 26 charities that received donations from the couple's Royal Wedding Charitable Gift Fund, which they set up at the time of their 2011 wedding.