The 29-year-old singer revealed she headed to the doctor who told her she'd damaged her vocal chords.
Adele's letter admitted she tried everything to finish her huge world tour that has seen her play 121 shows for fans all around the world.
"I'm already maxed out on steroids and aids for my voice," she wrote, even admitting she'd considered miming but "cannot in a million years do that to you".
The final two Wembley shows were supposed to happen on July 1 and July 2 at Wembley Stadium where she was expected to perform for close to 100,000 people. It would also be her 122nd and 123rd shows - a record-breaking feat on a tour that has already broken records in almost all the cities she's played in.
Adele's devastation over having to cancel shows because of her vocal chords isn't the first time the singer has had issues with her throat.
She was forced to cancel two tours in October, 2011 because of a vocal chord haemorrhage and had surgery a month later to remove polyps in her throat.
After her throat microsurgery, she made her comeback at the 2012 Grammys in February where she performed live and whom all six categories her album 21 was nominated in.
Adele started her world tour in the UK on February 29, 2016.