Rare handwritten poems by Emily Brontë, works by Robert Burns and Jane Austen first editions are included in the collection.
Friends of National Libraries (FNL) have raised over £15m to acquire the Honresfield Library, which houses the works, and say they intend to keep it in the public domain.
The library has been largely inaccessible for the last 80 years.
It was curated towards the end of the 19th century by Rochdale mill owner William Law. He gathered manuscripts and printed books written by literary giants from England and Scotland.
Auction house Sotheby's announced the sale of the library, in three tranches, in May 2021.
Emily Bronte's poems had been expected to fetch between £800,000 and £1.2m, and a first edition of her novel Wuthering Heights between £200,000 and £300,000.
However, FNL successfully petitioned the agents to postpone the sale.
The delay allowed the charity to raise sufficient funds to purchase the entire collection outright on behalf of libraries in the UK
Following the purchase, FNL said the collection will remain permanently in the public domain and never be lost to overseas institutions or to private collections that are inaccessible to the British public
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