"I have taken over a big British club, with a great support, and I'm looking forward to working in the Premier League again," said Moyes.
Sunderland chairman Ellis Short said Moyes was "first choice" to take control of the Black Cats.“We are absolutely delighted to welcome David Moyes to Sunderland, who was by far and away our first choice," chairman Ellis Short said.
“He is a man whose football pedigree speaks for itself and is someone I have long admired. I have spoken with him on many occasions and I have always been hugely impressed.
"He was my number one managerial target for the last five appointments, but his desire to honour existing contracts meant we were not able to bring him to Sunderland previously. To be able to finally welcome him as our manager is fantastic news for the club.
“The fact that David has committed to a four-year deal is a clear demonstration of his belief in what he can achieve here.
"It is our aim to become a better, stronger and more stable football club and with a manager of David’s calibre and experience at the helm, we have a fantastic opportunity to begin looking upwards, rather than downwards every season”.
The Scot has been out of work since being sacked by Spanish club Real Sociedad in November.Allardyce was confirmed as Roy Hodgson's successor with the national team on Friday.