The announcement was made in an memo to employees signed by CEO Jamie Dimon and co-Presidents and Chief Operating Officers Daniel Pinto and Gordon Smith.

Lake will continue to serve as a member of J.P. Morgan's operating committee and will be joined by Piepszak.

Piepszak, currently chief executive officer for card services, will assume the role on May 1. Outgoing CFO Marianne Lake will become CEO of the consumer lending business, which includes card services, home lending and auto finance.

J.P. Morgan Chase has tapped Jennifer Piepszak as its new chief financial officer, according to an internal memo seen by CNBC on Wednesday.

The memo described both women as "extraordinary executives and leaders who have been critical to our success."

In her 25 years at J.P. Morgan, Piepszak has held a number of senior roles in the corporate and investment banking business, as well as the consumer and community banking division.

Lake has long been considered a top contender to succeed Dimon as CEO when he retires in about four years. She has served as CFO of J.P. Morgan, the largest U.S. bank by assets, since 2012.

In her new role, Lake will gain more direct experience in running a business unit within J.P. Morgan. This would complement her background in broader corporate roles at the bank. It also suggests Lake is the frontrunner to succeed Dimon.

In an interview with Reuters published in September, Lake said she was ready to take on a different role at J.P. Morgan. At the time, she said the next CEO's main challenge will be making sure J.P. Morgan remains the country's most profitable big bank.

"When you are a successful company," she told Reuters, "you have to fight really hard to make sure you avoid complacency, arrogance, bureaucracy."