Initially it is offering investors a choice of 10 managed funds through RaboPlus, its online subsidiary.
RaboPlus had a tilt at retail banks and finance firms 16 weeks ago when it offered online call accounts and term deposits.
Netherlands-based Rabobank has operated here for many years but had restricted its activities to the rural sector.
Although RaboPlus is targeting the wider retail market, general manager Mike Heath said it was restricting business to deposits and would not offer transactional accounts and loans.
It is giving investors direct access to funds managed by AMP, Tower and Asteron and, unlike most banks, is not repackaging them as its own products.
Heath claims the online model gives investors significant advantages, including lower fees, less restrictive terms and greater convenience.
The minimum investment is $250 and there is no requirement to maintain a regular contribution. Many funds require a minimum initial investment of $1000 and additional contributions each month.
The entry fee is 0.75% of the amount invested, and management fees are 1% to 1.5% a year. There are no exit fees, making it easier for investors to cash up or switch between funds.
Average annual returns over three years on the funds being offered have ranged from 4.71% to 19.6%, depending on their investment profile.
"With RaboPlus you could invest $250 in one of our funds and then never put another cent into it if you didn't want to. And you could cash up whenever you want and there's no penalty," Heath said.
"It has the flexibility of allowing you to invest as little or as much as you want, without being tied to it."
Heath said the company was targeting the growing numbers of people who were financially savvy and felt comfortable actively managing their own finances without having to work through an adviser.
To help prospective investors decide on best options, the RaboPlus website has an online evaluation programme. Investors answer a series of multichoice questions and the programme classifies them either as a "saver" or "investor."
Savers are directed to the high-interest call account or term deposits, and investors answer more questions to determine what returns they want and their preferred level of risk.
It then recommends the fund or funds that most closely match their needs.
Heath said 6000 customers had invested $250 million in online call accounts and term deposits since they were launched in February.