Dortmund confirmed the two teams had reached a “mutual agreement” over the transfer of the 19-year-old in the summer.
It is understood the deal will guarantee Dortmund £88.5million – but will rise towards £113.5 million as a result of £25m worth of performance-related add-ons – which are believed to be achievable.
One of the most promising talents in world football, Bellingham joined Dortmund from Birmingham City in 2020 for a fee of €25 million.
He has played 132 games for the club, scoring 24 goals and winning the 2021 German Cup.
Bellingham was named Bundesliga player of the season after the 2022-23 campaign, when he helped Dortmund to within an inch of their first Bundesliga title in over a decade.
Dortmund finished second, behind Bayern Munich, on goal difference after dropping points on the final matchday against Mainz, where the injured Bellingham watched from the bench.
Making his debut for England at just 17, Bellingham played a starring role in the Three Lions’ 2022 World Cup campaign.
Bellingham started each of England’s five matches in Qatar, scoring once and assisting another as his side made it through to the quarterfinals, where they lost against eventual runners up France.