Gadhia last month took on the chairmanship of digital wealth manager Moneyfarm, replacing co-founder Paolo Galvani to work alongside CEO and co-founder Giovanni Daprà.
Gadhia was at the helm of Virgin Money, the digital bank of Britain's Virgin group, for more than a decade until its listing in 2018.
UniCredit said Gadhia had decided to step down "due to a new commitment" and would remain as an adviser to the bank.
UniCredit's current board comes up for renewal in spring 2024.
(Reporting by Valentina Za; Editing by Kirsten Donovan)