Publisher Random House had reported to police it discovered a finished copy of the book had gone missing last Monday.
But Kent Police said it found no proof a crime had taken place.
The book, which re-tells the first instalment of the hit trilogy from billionaire Christian Grey's point of view, is due to be released on 18 June.
"Following a report that one book had been stolen after packaging was found to be damaged, there is no evidence at this stage to suggest that an offence has been committed," a Kent Police spokeswoman said.
"No more action will be taken unless further information is received."
In a statement, Random House said: "We are delighted that the book's theft does not appear to have been for any malicious intent or financial gain.
"We can however confirm that we will continue our investigations into this matter and that we will be reporting any findings to Kent police."
The Fifty Shades of Grey trilogy has sold more than 125 million copies worldwide since the first book's release in 2011.
The first book was released as a film earlier this year.
Police say they have found "no evidence" to suggest a copy of EL James's latest Fifty Shades novel was stolen ahead of its release.