The pair are believed to have cost just £5.5 million, according to the Sunderland Echo, having completed their medicals yesterday afternoon, and are expected to be ready for the game with Manchester City this weekend.
Moyes took charge of the Red Devils for the 2013-14 season and was more than keen to turn to the youth, and both McNair and Love clearly impressed him that season with him choosing to bring them to Wearside now.
Paving the way?
With centre-back Lamine Kone having been in talks with Everton this week regarding a move to Goodison Park worth more than £18 million, the arrival of McNair provides Sunderland with another option in the heart of defence should the January signing depart.
Kone did however return to Wearside after being pictured in a Merseyside hotel, giving the fans some hope that the deal may be off.
If it doesn't go through, McNair is still a welcome recruit though. While Kone and Younes Kaboul would likely be the first choice centre-back pairing, third-choice John O'Shea is 35-years-old now and lacks the pace of his fellow defenders.
McNair is a man at the opposite end of the career spectrum, and the 21-year-old could learn a lot from O'Shea as he bids to enjoy an established career of his own.
Right-back gap filled?
Meanwhile, Love's arrival gives the Black Cats a well-needed option on the right hand side of defence.
Following DeAndre Yedlin's return to Tottenham Hotspur, the American having spent last season on loan with Sunderland, a gaping hole in the back line suddenly appeared.
It seemed that Yedlin would return to fill it again, but neither a permanent switch to Wearside nor another temporary one seems close to materialising, even with him out of favour at Spurs.
Billy Jones and Adam Matthews are the other right-backs on the books, but the former's pre-season injuries have him a doubt for Saturday's Premier League opener, while the latter has joined Bristol City on loan.
The chance to be a first choice right-back in the Premier League is a very real one for 21-year-old Love - who impressed in his United debut against the Black Cats back in February of this year.