As a moving tribute to her beloved Philip, the monarch wore her 'Scarab' brooch, which was designed by Andrew Grima. The beautiful yellow gold, ruby and diamond brooch was a personal gift from her husband in 1966, and she memorably wore the jewel for her and Philip's platinum anniversary portrait.
WATCH: The Queen arrives at Prince Philip's service of thanksgiving
The Queen dressed in an elegant forest green coat for the occasion, which she teamed with a matching green hat with maroon trim. The monarch wore pearl earrings and black gloves.
The Duchess of Cornwall and Princess Anne also dressed in green. The choice of colour was seemingly a subtle tribute to Philip, whose livery colour in the armed forces was Edinburgh Green.
The Queen pays tribute to her late husband
It was announced earlier on Tuesday morning that the Queen would be in attendance following reports that she may not be well enough to travel to London
The Queen wears her beautiful scarab brooch
Senior royals attended the service of thanksgiving to pay tribute to Prince Philip's dedication to family, the nation and the Commonwealth and in particular his contribution to public life.
The Queen stood beside her son Prince Charles at the service
Also in attendance were Prince Charles and Duchess Camilla, the Duke and Duchess of Cambridge with their children Prince George and Princess Charlotte, Princess Anne and Sir Tim Laurence, and the Earl and Countess of Wessex along with their teenage children Lady Louise Windsor and James, Viscount Severn.
The Queen has been actively involved in the plans for Tuesday's memorial service, which incorporates some elements initially planned for Philip's funeral that were unable to go ahead due to the government's COVID restrictions at the time.
These include hymns being sung, such as Guide me, O thou great Redeemer, which Philip had requested for his funeral as well as clergy from the royal estates of Windsor, Sandringham and Balmoral playing a part in the service, another of the Duke's requests.
The monarch sits with members of the royal family
The memorial event also recognises the importance of Philip's legacy in creating opportunities for young people, promoting environmental stewardship and conservation, and supporting the armed forces. The 700 charitable organisations he supported throughout his life, as well as his eponymous The Duke of Edinburgh Award, feature prominently in the service as well.
The Queen's husband of 73 years sadly passed away aged 99 on 9 April 2021 and his funeral was held just over a week later, with only 30 people in attendance at St George's Chapel in Windsor.