Jes Staley has been promoted from head of the asset management unit to investment bank chief executive officer, a move that is believed to bode well for his chances of eventually landing the top job at the firm.
Analysts have said that Mr Staley's promotion to one of JPMorgan's most profitable operations marks him as a likely candidate to replace Mr Dimon in the future.
He has worked for the company since 1979, becoming head of corporate finance for Brazil in 1980 and was one of the founding members of JPMorgan's equities business, which saw the firm begin its expansion into investment banking.
The other manoeuvres in the higher echelons of the company have seen the co-chief executive officer of the investment bank, Bill Winters, leave the firm.
Mr Dimon said of the departure of Mr Winters: "With the credit crisis largely behind us and the economy recovering, the timing was right to begin the succession process."
He thanked Mr Winters, who became co-CEO for JP Morgan in 2004, for his 26 years of service to the company.
Mr Winters, who, according to the Financial Times, owns around $58 million in company shares, said he was looking forward to his next professional challenge.
He added that he was proud of being part of the team that has successfully led the business through the turmoil of the last 18 months.
JP Morgan's investment bank largely managed to avoid the complex debt securities that led to the subprime crisis and caused large losses for many of its rivals.
Anther change will see Steve Black, the other investment banking co-chief executive officer, become executive chairman of investment banking.
Meanwhile Mr Staley's former job will be taken by Mary Callahan Erdoes, who was previously chief executive of JP Morgan's private bank.
By Claire Archer