Ole Gunnar Solskjaer will get the financial backing to bring success back to Manchester United, says executive vice-chairman Ed Woodward.
United finished sixth in the Premier League this season.
"The strength of our business means we have the financial resources to continue to provide backing for the manager and creating success on the pitch," said Woodward.
"This as ever remains our number one goal."
Solskjaer took over as caretaker United boss in December following the sacking of Jose Mourinho and the club went on a run of 11 games without defeat, of which they won 10.
However, after the Norwegian was appointed on a permanent basis in March, his side's form collapsed and they finished five points off the top four having won only two of their last nine games.
Solskjaer, whose side were 32 points adrift of champions Manchester City, has said it will "take a long time" for Manchester United to challenge for the Premier League title again.
The Old Trafford club last won the title in 2012-13, in Sir Alex Ferguson's last season in charge, while it is now two seasons without a trophy after the Europa League and League Cup triumphs in 2016-17.
"While the last few weeks were disappointing, we are delighted to have confirmed the appointment of Ole as our manager on a three-year contract," said Woodward.
"Everyone at the club – the board, the manager, the squad and all the staff are resolute in our desire to get United back to the top of English football, we continually look to improve staff on and off the pitch to achieve this."