William was overheard describing the charred remains of the apartment block as "one of the most awful things I have ever seen", while the Queen appeared stoic as she was briefed on the recovery effort.
The British capital was also struck by a terrorist attack earlier this month, in which eight people died when three attackers drove into pedestrians on London Bridge and then went on a stabbing rampage.
Along with the queen and her husband, Prince Philip, Prince William and Kate Middleton brought out their adorable kids, Prince George and Princess Charlotte, to enjoy the morning.
"It is hard to escape a very sombre national mood", Elizabeth, the world's oldest and longest-reigning monarch, said in a message on her official birthday.
Some residents had warned months ago that the tower represented a risky fire risk.
Prime Minister Theresa May has ordered a public inquiry into the Grenfell Tower fire.
The Queen's actual birthday was on April 21, when she turned 91. Britain's Press Association says around 70 people are missing.
Londoners and others have also donated huge amounts of food, water and clothing, and shelter, to survivors.
Rescue personnel have had difficulty reaching the top floors of the charred, 24-story tower. Her visit followed protests over the deadly fire.
Scuffles broke out near the Kensington and Chelsea town hall offices Friday as demonstrators chanting "We want justice!" surged toward the doors.