The 21-year-old had been in intensive care since being hit by a vehicle in Bristol last month, but her condition worsened, and a friend confirmed she had died on Saturday (6 May).
After news of her death broke, Josh Cuthbert, Jaymi Hensley and JJ Hamblett all took to Twitter to pay their respects.
George has yet to comment on his sister’s death.
The ‘I’m A Celebrity’ 2015 runner-up left Union J shortly after his appearance on the ITV reality show, with his spokesperson later labelling his former bandmates ‘jealous’ after he was told he was no longer in the boyband.
They went on to replace him with former Stereo Kicks singer Casey Johnson, who has since announced his departure from the group, less than a year after he joined.