ING Direct Australia (IDA) chief executive Erik Drok will leave his role at the end of May when his contract finishes.
Drok has been assigned to an unknown post within the firm's global parent ING Group NV, an industry source said.
It is understood Drok's replacement has been selected from within ING Group and will be announced within weeks.
The Amsterdam-based ING Group operates in 50 countries.
Drok has been in the role for three and a half years. Under his tenure, IDA posted record profits during 2007 and 2008.
The firm also carved a strong brand name in the DIY super, online savings accounts and term deposit segments through hiking rates and aggressive marketing.
IDA is Australia's fifth-largest retail bank with approximately $20 billion in deposits, around $30 billion in loans and over 1.25 million customers.
