Hammers boss David Moyes wants Lingard, a player he knows from his time in charge at the Red Devils, to strengthen his squad as they look to build on their impressive start to the season.
England midfielder Lingard, 28, has fallen down the pecking order at Old Trafford and will see a temporary switch as a chance to reignite his career.
PA understands West Ham have agreed to pay United a £1.5million loan fee and cover Lingard’s wages.
First West Ham must free up a domestic loan space in their squad, which will see Said Benrahma complete his permanent move to the London Stadium.
Algerian forward Benrahma was signed initially on loan on deadline day during the last transfer window after an issue with his medical, with the move set to be made permanent in the summer.
But PA understands that transfer, £25million plus £5m in add-ons, will now go through in the next few days.
Defender Craig Dawson is West Ham’s other loanee, from Watford, and his performances in their six-match winning run have also warranted a permanent deal.