The 28-year-old will replace Harry Maguire, who was stripped of his captain's armband by Erik ten Hag for failing to secure a place in the starting lineup.
Bruno Fernandes has 64 goals and 54 assists in 185 appearances for Man United in all competitions. He was often the captain when Maguire was absent last season.
British media said the Old Trafford team was ready to listen to Maguire's offers. Currently, West Ham is the team most interested in the English centre-back.
"The Portuguese midfielder has been capped by Man United on several occasions and Erik ten Hag has confirmed that he will take on the role for a long time," Man United said in a statement.
"As captain and a two-time winner of the club's Player of the Year award, we will continue to promote the highest standards in the whole team as Man United aim for success in the 2023-2024 season and beyond."
Fernandes was criticized for his hot performance in the 0-7 loss to Liverpool last March.
Man United's pre-season campaign is going smoothly as they have just defeated the team playing in Ligue 1, Lyon with a score of 1-0.
Next, the "Red Devils" will go to the US to face Arsenal, Wrexham, Real Madrid and Dortmund in friendly matches before the new campaign.
