David Moyes will succeed Sir Alex Ferguson as Manchester United manager on a six-year deal starting on 1 July.
Moyes, who leaves Everton after 11 years in charge at Goodison Park, was Ferguson's recommendation to succeed him as manager at Old Trafford.
The 50-year-old was out of contract at Everton at the end of the season.
"We unanimously agreed on David Moyes," said Ferguson, who announced his retirement on Wednesday after 26 years as United boss. David is a man of great integrity with a strong work ethic. I've admired his work for a long time and approached him as far back as 1998 to discuss the position of assistant manager here. There is no question he has all the qualities we expect of a manager at this club."
Moyes, who was recommended to the United board by Ferguson and will be introduced as Red Devils boss in "due course", said it was "a great honour" to be appointed as the new manager of the Premier League champions.
"I am delighted that Sir Alex saw fit to recommend me for the job. I have great respect for everything he has done and for the football club," added the Scot.
"I know how hard it will be to follow the best manager ever, but the opportunity to manage Manchester United isn't something that comes around very often and I'm really looking forward to taking up the post next season."
Moyes, described as having "all the skills needed to build on United's phenomenal legacy" by incoming chief executive Ed Woodward, also paid tribute to current club Everton and vowed to remain fully committed until the end of the season.
"I have had a terrific job at Everton, with a tremendous chairman and board of directors, and a great set of players," he said. "Between now and the end of the season, I will do everything in my power to make sure we finish as high as possible in the table. Everton's fantastic fans have played a big part in making my years at Goodison so enjoyable and I thank them wholeheartedly for the support they have given me and the players. Everton will be close to me for the rest of my life."