The Belgian was superb aboard Rainman to seal the title in style at Greenwich Park, finishing with a personal-best score of 82.100 per cent.
That was enough to hold off the challenge of Great Britain's Sophie Wells aboard Pinocchio (81.150 per cent).
Netherlands' Frank Hosmar and Alphaville claimed bronze to complete an exact repeat of the placings in the Championship Test - Grade IV competition on Day 4.
George was overwhelmed by her victory, saying: 'I am lost for words. To achieve this in a country like [Great Britain] with such a strong tradition. I really felt the pressure. I really enjoyed it but it was hard to keep him calm.
'It was really important to me. An achievement coming here to this venue - I just can't find the right words to tell you how important it is.'
It was another familiar story in Grade III, where Hannelore Brenner dominated again by winning gold on Women of the World after scoring 81.700 per cent.
The German followed up her victory in the Individual Championship Test competition by triumphing once more, with Deb Criddle of Great Britain on LJT Akilles (78.550) winning her second silver ahead of Denmark's Annika Dalskov on Aros A Fenris (76.950) in bronze again.
Sophie Christiansen then became Great Britain's first triple gold medallist of London 2012.
The 24-year-old also secured a British Paralympic record 11 medals in one Games for Britain's Equestrian team.
Christiansen, riding Janeiro 6, added Freestyle Test - Grade Ia gold (84.750) to a Team gold medal and Championship Test - Grade Ia title.
Laurentia Tan (79.000) claimed silver on Ruben James 2, with Ireland's Helen Kearney (78.450) third on Mister Cool.