Louis van Gaal's side have struggled to entertain this season and have netted just 22 league goals to date, with only 10 of them coming at Old Trafford.
Wayne Rooney and Anthony Martial are United's only recognised strikers after Robin van Persie, Javier Hernandez and Radamel Falcao were allowed to move on in the summer, followed by James Wilson's exit to Brighton on a season-long loan.
United can recall the England Under-21s striker but have instead decided to bring back Keane, who has netted twice in 22 appearances for Sky Bet Championship outfit Preston.
The 22-year-old's sole first-team appearance for United came as a late substitute in a home loss to Blackburn on New Year's Eve 2011, but Preston manager Simon Grayson suggests he would be in the first-team fold at Old Trafford.
"(It happened) in the last 24 hours or so," he told Sky Sports News.
"United felt they needed an extra body around them.
"Obviously it's disappointing to lose Will
In the last few weeks he's been finding his feet with us, but that is what happens when you get loan players.
"We accept it
We will probably go into the market over the next few days and weeks to bring in reinforcements
Hopefully he will do well for Manchester United."
Asked if Keane could answer United's goalscoring problems, Grayson said: "It's a big step up
But he's played regularly for us, he's fit, so time will tell."
Keane won the Jimmy Murphy Young Player of the Year in 2010 and has spent time at loan with Wigan, QPR and Sheffield Wednesday before joining Preston on a season-long loan.
Source : PA