Police responded after several people reported to 911 that a man was chasing people around the park.
Officers arrived and found a woman who told them she had been sexually assaulted.
She was later transported to the hospital.
Officers found the 25 year old suspect in a parking garage near the Seattle Art Museum Sculpture Park and he was arrested.
Jamieson said the man had an outstanding warrant for failing to register as a sex offender.
He was booked into the King County Jail.