The Foxes must wait for Premier League clearance but the young pair look set to add depth to Nigel Pearson's squad as they look to establish themselves in the top flight
Lawrence has signed a four-year deal after a reported fee of £2 million was agreed while Powell moves on a season-long loan deal, though both deals are subject to Premier League clearance.
Twenty-year-old Lawrence only made his debut for the Red Devils in the win over Hull City in May, and despite being compared to Ryan Giggs during his time with the club's academy, will not be given the chance to prove his credentials at Old Trafford.
Powell, meanwhile, spent the 2013-14 campaign on loan at Wigan Athletic and will look to continue his development by playing Premier League football with the newly-promoted Foxes.
Should their deals be ratified, the pair could make their debuts for Nigel Pearson's side against Stoke City on September 13, though Powell will be inelgible to play against his parent club the following week.
The duo join fellow youngster Michael Keane in leaving the club on deadline day as the defender joined Burnley on loan until January.