Borussia Dortmund's players sang The Beatles' classic "Hey Jude" to welcome their newest teammate to the club.

Dortmund on Monday confirmed the signing of promising 17-year-old English midfielder Jude Bellingham from second-division club Birmingham.

Dortmund said Bellingham signed a "long-term deal" and will wear the No. 22 jersey. Kicker magazine reported Dortmund paid 25 million euros (NZ$43 million) for the transfer.

"I'm incredibly excited to have joined one of Europe's biggest clubs," Bellingham told Birmingham's website. "The direction they are heading in and how much they help to improve young players made it an easy decision for myself and my family."

The long-discussed deal was announced two days before Birmingham's final league game of the season – a potential relegation decider against Derby. Bellingham will join his new Dortmund teammates on July 30.

"He already boasts astonishing quality with and without the ball, and has a strong mentality to boot," Dortmund sporting director Michael Zorc said. "Jude will immediately strengthen our first team squad, but we will certainly give him all the time he needs to adapt to the higher level of play."

Bellingham follows in the footsteps of England forward Jadon Sancho, who was 17 when he made the move from Manchester City to Dortmund three years ago. Sancho has since become one of the Bundesliga's most valuable attacking players with 17 goals and 17 assists this season.

Bellingham made his debut for Birmingham last August, aged 16 and 138 days. That made him the youngest player in the club's history. He went on to score four goals in 40 league appearances.

Bellingham also has two goals in three appearances for England at the under-17 level.

Bellingham is Dortmund's second signing for the upcoming season after right back Thomas Meunier arrived on a free transfer from Paris Saint-Germain. It's unlikely there will be any more unless Sancho leaves the club.