Queen Elizabeth II's granddaughter trotted High Kingdom before a panel of judges and a veterinarian on Tuesday. They were looking to see if he had recovered from the arduous cross-country competition Monday in Greenwich Park.
The judges declared High Kingdom "accepted," and a cheer erupted in the stands.
Phillips helped put Britain in gold-medal contention with a penalty-free ride on Monday. Germany leads the team standings, with Sweden in third.
Phillips was cheered during the cross-country event by cousins Princes William and Harry, raising hopes the queen may attend Tuesday's final.