A picture of Princess Charlotte expertly posing for a portrait on her 5th birthday was liked 785,000 times.
However, the remaining six pictures which received the most likes all featured the Queen - solidifying her position as one of the most popular members of the Royal Family.
One shows her and husband, the Duke of Edinburgh, in the quadrangle at Windsor Castle in June to mark his 99th birthday (808,000 likes). The Queen is wearing a dress with bright yellow flowers on it, while the Duke sports a navy suit and matching tie.
The couple are also pictured together at Windsor Castle in November, sitting side by side reading through cards and letters they received to congratulate them on their 73rd wedding anniversary (811,000 likes).
Older black and white pictures of the Queen and her husband also proved popular.
One shows the couple staring lovingly into each other's eyes while on their honeymoon in 1947 at Broadlands in Hampshire (707,000 likes). Another, taken two years later, shows the pair beaming as they hold a baby Prince Charles, then aged six months (709,000 likes).
Among the other most popular shots was the Queen knighting Captain Tom Moore, the World War II veteran who raised millions of pounds for the NHS by walking laps of his garden using a zimmer frame (639,000 likes).
It shows the Queen, wearing one of her trademark colourful coats, this time in pastel green, placing the ceremonial sword on Captain Tom's shoulder on the lawn at Windsor Castle.
The final image which attracted among the most likes (746,000) is a portrait of the Queen standing with Prince Charles, Prince William and Prince George at Buckingham Palace.
Taken in January, the picture of three generations of royal men was captured to mark the beginning of 2020 and a new decade.
The analysis was carried out by Gert's Royals, a royal blogger, and the findings were published on Twitter.
It comes after Kensington Palace revealed that the Duke and Duchess of Cambridge had carried out 180 and 120 engagements respectively this year - and, like many parents, had been "juggling homeschooling" with their work.