This marks Prince Philip's first public appearance since undergoing hip surgery last month.
The two were spotted arriving to the Cliveden House Hotel on Friday.
The Duke of Edinburgh will be present at his grandson's Saturday nuptials.
ET is on the ground outside Windsor Castle, where Prince Philip dropped off the queen to watch some of her own horses compete in the Royal Windsor show.
The 96-year-old royal drove the Queen to the Royal Windsor Horse Show on Friday.
The Duke of Edinburgh's recovery continues!
The Duke of Edinburgh is 'comfortable and in good spirits,' according to a statement from the royal family.
The 96-year-old royal will undergo surgery after experiencing trouble with his hip.
But where were Meghan Markle, Prince Harry and Prince Philip?
The 96-year-old royal chose not to attend the traditional royal Maundy service at St. George's Chapel on Thursday.
The retired royal was supposed to attend the service alongside his wife.
The longtime spouses are both celebrating milestone birthdays this weekend.
