Cavani, 33, has been a free agent since leaving Paris Saint-Germain in June. The Uruguay international signed a one-year deal with the option for a second season at Old Trafford.
During seven years at the Parc des Princes, Cavani scored 200 goals to become the club's record goalscorer and a favourite of the fans for his all-action attitude and fighting spirit.
But despite his prowess and popularity, the club’s hierarchy preferred to ditch him and focus a front line around Kylian Mbappé, Neymar, Mauro Icardi and Angel di Maria.
Cavani's arrival in north-west England has raised the intriguing prospect of a match against his former employers as Manchester United and Paris Saint-Germain have been drawn in the same group in the Champions League.
Honour
"Manchester United is one of the greatest clubs in the world,” said Cavani. “So it is a real honour to be here. I've worked really hard during the time off and I feel eager to compete and represent this incredible club.”
United have made a disastrous start to the 2020/21 Premier League season. They lost their opening game 3-1 at home to Crystal Palace, won their second away at Brighton 3-2 but went down 6-1 at home to Tottenham Hotspur.
In an attempt to seal the breaches, boss Ole Gunnar Solskjaer has drafted in the left-back Alex Telles from the Portuguese champions Porto for 15 million euros.
"He is a player we have been tracking for some time and his performances over the past few years are exactly what we are looking for," said Solskjaer of the Brazil international.
"He is a fighter and a winner and will add real determination and competition to the squad."
