USR Parent Inc, or Staples, said it would offer $40 for each ODP share, a premium of 8.2% to Friday's closing price. They were last trading at $43.85.
The two companies agreed to merge in 1996, but the deal was put to rest as a government lawsuit argued the move would have meant higher prices for pens, paper and other office supplies.
Staples' second attempt, a $6.3 billion offer in 2016, was blocked by the U.S. Federal Trade Commission saying the merger could reduce competition for nationwide contracts for office supplies.
Since the first offer, new rivals such as online retailer Amazon as well as supermarkets Walmart and Costco have crowded the market and e-commerce has boomed.
During the COVID-19 pandemic, the shift to online shopping helped office retailers as the demand for stationary and other learn-from-home products rose.
Staples, which was taken private by Sycamore Partners in 2017, said it is prepared to take "all necessary measures" to divest ODP's commercial business unit to satisfy any regulatory objections.
The retailer said it would raise the offer if ODP begins a sale of its commercial business unit or divests its CompuCom business, an IT solutions provider.
"Staples has sufficient resources to finance the transaction," the company said. "Our obligation to proceed with the transaction is not subject to a financing contingency."
ODP said it was reviewing the offer, taking into account potential antitrust and other regulatory challenges given the previous outcomes.
Office Depot became a unit of newly created ODP Corp last year, following a 1-for-10 reverse stock split and broader reorganization.
(Reporting by Nivedita Balu in Bengaluru; Editing by Bernard Orr, Maju Samuel and Arun Koyyur)
