Cavani is due to fly into Manchester for a medical ahead of signing a one-year deal with the option of extending his stay until 2022.
The 33-year-old has been without a club since bringing his seven-year stay at Paris Saint-Germain to a close this summer at the end of his contract.
Cavani is expected to command significant wages at Old Trafford, though these will be partially offset by the lack of any transfer fee in the deal.
United consider the Uruguay international to be a proven winner who fits into the recruitment philosophy of combining high-quality recruits with homegrown talent.
It is hoped that Cavani will be able to support the development of younger players, particularly the likes of Anthony Martial, Marcus Rashford and Mason Greenwood in United’s attack.
The Uruguayan will provide cover for Martial with on-loan Odion Ighalo returning to Shanghai Shenhua in January. Cavani scored 200 goals in 301 appearances for PSG.
United are yet to give up hope of securing their priority transfer target Jadon Sancho from Borussia Dortmund, though protracted negotiations remain at an impasse.