Ten Hag will leave his job at Ajax at the end of the season to become United’s fifth permanent manager since Sir Alex Ferguson retired in 2013.
The 52-year-old will be joined at Old Trafford by his No 2 Mitchell van der Gaag.
The Dutchman’s appointment has been expected for some time. since Sportsmail revealed a month ago that he had been interviewed for the job having moved ahead of Paris Saint-Germain boss Mauricio Pochettino.
United confirmed the news in a statement on Thursday morning.
Ten Hag said: ‘It is a great honour to be appointed manager of Manchester United and I am hugely excited by the challenge ahead.
‘I know the history of this great club and the passion of the fans, and I am absolutely determined to develop a team capable of delivering the success they deserve.
‘It will be difficult to leave Ajax after these incredible years, and I can assure our fans of my complete commitment and focus on bringing this season to a successful conclusion before I move to Manchester United.’