The royals were seen at the Berkshire racecourse where the Queen's previously unbeaten horse Estimate was racing.
Britain's monarch, who was accompanied by her husband the Duke of Edinburgh and her racing manager John Warren, was dressed in a cream, pink and brown checked coat. The Queen's elegant look was completed with a light pink hat and a black patent handbag and heels.
Beatrice, 25, chose a more wintery outfit and stepped out in a dark grey coat and a navy blue hat.
Appearing to be in high spirits and smiling broadly the Queen was seen speaking to her jockey Ryan Moore, who finished in seventh place following three unbeaten races at Ascot.
Princess Beatrice and her 23-year-old sister Eugenie joined in with the Queen celebrations in June when Estimate most recently stormed to victory at Ascot.
Prince Andrew's daughters, along with their father, Princess Anne and Peter and Autumn Kelly, were photographed jumping for joy as Her Majesty's horse took first place.
Presenting duo Ant and Dec were among the other racegoers as was TV presenter Jeremy Kyle and his wife Carla.