The Portugal international will replace Harry Maguire, who was stripped of the captaincy last week after losing his place in Erik Ten Hag's starting eleven last season.
Fernandes has skippered Manchester United on several occasions in the past but will now keep the armband on a permanent basis.
The 28-year-old has been one of Manchester United's best players since signing from Sporting Lisbon in the 2020 winter transfer window.
An official statement on the Red Devils' website read: "Bruno Fernandes has been named as the new club captain of Manchester United.
"The Portuguese midfielder has already worn the armband for United on numerous occasions and Erik ten Hag has confirmed that he will now lead the team on a permanent basis.
"Fernandes has scored 64 goals and contributed 54 assists in just 185 games for the club since joining in 2020.
"As captain, the two-time Sir Matt Busby Player of the Year will continue to drive the highest standards throughout the squad as United push for success in the 2023/24 season and beyond."
