Watch FULL MATCH REPLAYS & more via MUTV 24/7 on beIN SPORTS | Sign up to take advantage of our 7-day FREE TRIAL here | AU | NZ

The transfer fee is €76.5 million ($136.4 million) with €8.5 million ($15.2 million) in bonuses.

The 22-year-old Sesko, who joined Leipzig from Austrian club RB Salzburg in 2023, scored 39 goals in 87 appearances across all competitions for the German side.

"The history of Manchester United is obviously very special but what really excites me is the future," Sesko said via a statement.

"When we discussed the project, it was clear that everything is in place for this team to continue to grow and compete for the biggest trophies again soon ... It is clearly the perfect place to reach my maximum level and fulfil all of my ambitions.

"I cannot wait to start learning from (manager) Ruben (Amorim) and connecting with my team-mates to achieve the success that we all know we are capable of together."

Manchester United has also signed forwards Matheus Cunha and Bryan Mbeumo as well as left back Diego Leon for the new campaign, which starts at home to Arsenal on 18 August (AEST).

United has spent around £200 million ($412 million) since its 15th-place finish in the Premier League last season, the club's lowest position in the top flight for 51 years.

The four new signings will be introduced at Old Trafford before a friendly against Italian side Fiorentina this weekend.