The robot, built by Renishaw in Rhondda Cynon Taff, implanted probes into Denise Casey's brain.
Mrs Casey, of Skewen, Neath Port Talbot, was diagnosed at 31 and has suffered up to six fits a day for the past 20 years.
She said the preliminary success of the operation, previously not possible, "offered hope" to others.
The robotic arm allows surgeons to operate on epilepsy sufferers who were previously untreatable.
It is far more accurate at placing probes into a patient's brain and reduces the operating time significantly.
Mrs Casey has not suffered any fits since her operation in March and said her life had "improved 100%".
Before, she could not go out alone as a seizure would leave her not knowing where she was.
"It's been remarkable, they said it was a robot and you think of something like that in the films. I know it's only been a couple of weeks, but so far it has been wonderful," she said.
The surgeon who operated on Mrs Casey, William Gray, a professor of functional neurosciences at Cardiff University, said the robotic arm had "phenomenal accuracy".
He said the operation would normally take more than four hours, but with the robotic arm it took 55 minutes.
"I think it's a major step forward, this robot puts the instrument in the right place," he added.
Renishaw also makes 3D printed body parts which are used in operations in Welsh hospitals.
A woman with epilepsy has become the first person in Wales to undergo pioneering robotic surgery.