The woman in her 50s was found in the park off Cedar Road in Leicester at 4.45am on 3 August – she is now in a stable condition in hospital.
The man, 24, of no fixed address, was tracked down in Stoke-on-Trent and arrested him in the early hours of this morning.
Detective Inspector Mark Sinski, from East Midlands Special Operations Unit Major Crime, said: “Our thorough and detailed investigation into what happened during the early hours of August 3 is continuing and there are still a number of lines of inquiry that we are following.
“Today, officers have been deployed to the area around the park to ensure that no stone remains unturned in our investigation.
“This has included searching drains in Cedar Road and the surrounding area to see whether anything can be recovered that will help us in catching the person responsible for this brutal attack.”
Drains have been examined by officers and plants have been stripped back to allow officers to search the park.
CCTV has been viewed as part of the investigation and the scene was cordoned off.
Cedar Road residents have also been asked to come forward with any information that could help police as the inquiries continue.