Fashion designer Peter Morrissey is recovering in a Sydney hospital following emergency surgery for an aneurysm in his brain.

Morrissey was rushed to St Vincent's Hospital on Saturday morning after experiencing "the rapid onset of excruciating headache and nausea" on Friday night.

He was diagnosed with a small cerebral aneurysm, and underwent emergency surgery on Sunday at Prince of Wales Hospital.

Vascular neurosurgeon Dr Richard Parkinson, who operated on Morrissey, said he would make a full recovery.

"Peter has done brilliantly," Dr Parkinson said.

"He had a ruptured brain aneurysm which I operated on using a coiling technique which is non-invasive surgery.

"The aneurysm has been completely repaired."

The iconic Australian designer thanked his partner Sean Simpson for saving his life.

"I would not be here if it was not for my beautiful partner Sean, he acted fast and saved my life, and my twin sister Libby and brother Dr Chris Morrissey have been by our side," Morrissey said in a statement released on Monday.

"Thank you for the professional and prompt response from Dr Parkinson who has been beyond incredible and the staff at both St Vincent's and Prince of Wales."

Morrissey, who had already had holidays booked for July, will spend the month quietly at home in Sydney.