A semi-nude female protester on Saturday UK time interrupted proceedings towards the end of a minute of silence in memory of the Duke of Edinburgh outside Windsor Castle.
The funeral of Queen Elizabeth's husband of 73 years was taking place within the castle's walls.
The protester was shouting slogans against littering, animal abuse and pollution, a Reuters reporter said.
The woman then reportedly jumped onto a statue of Queen Victoria before she was taken away by police.
A sizeable crowd was outside Windsor Castle to wish the Queen and her family well, despite official advice to stay away due to the ongoing coronavirus pandemic.
Crowds defied COVID-19 restrictions to pay their tributes to Prince Philip as his body made the journey from Windsor Castle to St George's Chapel, a short distance away.
The Duke's coffin was borne on a specially modified Land Rover hearse, followed on foot by a procession of senior royals including Prince Charles and Princes William and Harry.
Queen Elizabeth followed the procession in the State Bentley as the coffin, carried on the bespoke Defender TD 130 in military green, made its way to Philip's funeral service at St George's Chapel in Windsor Castle.
Charles and Princess Anne followed the coffin on foot, followed by their brothers Edward and Andrew. Behind them were Charles's two sons William and Harry - evoking memories of the 1997 funeral of Diana when they walked as grieving boys behind their mother's coffin.
Philip, officially known as the Duke of Edinburgh, died aged 99 on April 9.
His naval cap and sword lay on top of the coffin, which was covered with the Duke of Edinburgh's personal standard featuring the Danish coat of arms, the Greek cross, Edinburgh Castle and the stripes of the Mountbatten family.