The 19-year-old, who featured in United's FA Youth Cup successful campaign in 2011, is available to compete in Blackpool's Championship match against Nottingham Forest tomorrow.
"I spoke to Moyesy on Wednesday, had a good chat about him and he's got bags of potential," manager Paul Ince told the club's official website. "He's only a young kid so I don't want to put too much pressure on him.
"We'll have a look at him and give him some minutes. Sometimes you've got to throw people in at the deep end to see how they get on."
Blackpool's move for Blackett comes after Jack Robinson was hit with a four-game suspension.