Her stunning Freestyle test aboard Dolton scored 86.927%, smashing the record of 84.750% set by Sophie Christiansen in London 2012.
Para-Dressage
“Today was just an emotional rollercoaster of happiness and joy.” Barwick drew in to the Freestyle when Rixt Van der Horst had to withdraw.
The Brits edged The Netherlands while the USA took the bronze ‒ their first Paralympic Team podium finish.
A tight medal race at the Paralympic Games saw Great Britain take the gold, The Netherlands silver and United States the bronze.
Two new Paralympic equestrian champions have been crowned at Baji Koen - Roxanne Trunnell (USA) and Tobias Thorning Jorgensen (DEN).
Winona Hartvikson and Lauren Barwick narrowly missed qualifying for the Individual Freestyle; three will go on to the Team Test.
Friday will see Grades I and III Individual Test medals decided and mark the start of competition for Canada's four para-equestrians.
The fiercest Para-Dressage competition yet is set to begin in Japan, featuring 77 athletes representing 26 countries.
The 2018 WEG team of Lauren Barwick, Winona Hartvikson, Jody Schloss and Roberta Sheffield has reunited in Japan.
At the NAF Five Star Hartpury Festival of Dressage CPEDI 3*, Sheffield and "Wonky Horse" scored three top-three finishes.