"The broad choice breaks the traditional KiwiSaver mould, where providers often only have one manager's funds available."
The fees charged will depend on which funds the investor chooses with the underlying fund fees ranging from 0.27 per cent per annum for a cash fund up to 1.54 per cent.
But the exact cost will depend on which funds the investor chooses and how much they invest in each fund.
InvestNow won't charge an admin fee on top of those underlying fund manager fees as it will be paid a distribution fee out of those fees.
Mike Heath, InvestNow general manager, said the total cost to the investor would depend on what proportion of their KiwiSaver money was in each of the funds that were chosen and the fees on those funds.
"Customers are only going to pay what fees the managers' charge for their underlying funds.
"The fee you are going to pay at the end of the day is going to be a weighted average."
Heath said its goal was to give Kiwis the ability to grow their wealth how they see fit.
While there was no limit on how many funds a person could choose they wouldn't recommend having all 28, Heath said.
"The idea is to give people sufficient choice. If you are a passive investor or into active or want to pick particular asset classes, it's about giving them enough choice so they can build a portfolio that is aligned to their preferences."
Heath said it expected the scheme to have widespread appeal because of two factors.
"Now that KiwiSaver is over 10 years old it is now becoming a material asset for people and people are becoming more engaged and taking more notice of it.
"At the same time I think the timing is right as well in terms of the work we have been doing and Sharesies and Hatch, we have lifted people's confidence and comfort in looking at investing and managing their own investments."
He said people's awareness of investing was just that much more now.
It will add more funds in the coming months, with Heath expecting there to be up to 35 available by January.
They would adding some wholesale funds in the coming months which retail investors would not normally have access to.
InvestNow already operates an online investment platform which offers non-KiwiSaver managed funds and term deposits to investors.
It launched in March 2017 and has over $600 million of investments from 30,000 investors through the platform.
InvestNow is owned by Implemented Investment Solutions (IIS), a Wellington-based investment business that manages over $4.5 billion on behalf of New Zealand investors and was set up by Edmonds in 2011.
IIS is 60 per cent owned by Edmonds and Emma Levy through Centric Investment Solutions, 15 per cent owned by global investment company Russell Investment Group, 15 per cent by Jonathan and Rebecca Eele and 10 per cent by Andrew Brockway.
Edmonds was previously head of sales and marketing at AMP Capital. Rebecca Eele is the chief executive of Mint Asset Management and owns the majority of it with her husband Jonathan while Brockway is investment and product manager at IIS.