The fund, which is worth around $42 billion, exists to help pay for future government superannuation for all New Zealanders.
Chief executive Matt Whineray said the fund's long-term objectives mean it can survive market volatility.
"As a long-term investor, we choose a risk level and that's a risk level we believe we can tolerate through time. We've got a very growth-oriented portfolio because we believe we're going to grow for a long period of time," he told Morning Report.
"As a result, we know we're going to get times like this where we know markets are severely impacted."
Whineray said they don't see coronavirus as creating a significant change in the fund's long-term assumptions.
"There's no doubt that there's a massive disruption and there's a big hole in front of us from an economic activity perspective. However, we can look through that as a long-term investor and say, we still believe we're going to get paid for owning equities over the long-term."
In the short-term, market volatility has resulted in shocks for many KiwiSaver investors.
For those looking at their savings online yesterday, there were some big drops in value.
Sam Stubbs, managing director of KiwiSaver fund manager Simplicity, told Morning Report global investments have gone on sale so, as a long-term strategy, you should stick with the fund you're in.
"Your average KiwiSaver fund has got about 3000 investments in over 25 countries, so it's extremely diversified. You've got to focus on the long-term," Stubbs told Morning Report.
"Markets, in the short-term, are voting machines and right now they're voting on fear and uncertainty and they hate uncertainty. But long-term financial markets are a weighing machine - logic wins in the end."
Stubbs said history shows that market downturns driven by pandemics always end up with markets higher 12 months later.
"That's because, ultimately, these things go away."
However, he said people considering buying their first home now should switch to conservative funds so they don't get a shock to their deposit.
And the Reserve Bank seems in no hurry to either slash the official cash rate or reach for the panic button to counter the Covid-19 virus impact on the economy.
Yesterday it unveiled a raft of measures - unconventional monetary policy tools - it could use to stimulate the economy if the normal cash rate mechanism proved ineffective.
The assistant governor Christian Hawkesby said there is no need to use them at the moment - but it's prudent to be prepared.
"Unconventional monetary policy is really about what we do when we run out of room with our conventional tools - and that's about the official cash rate getting at or near zero," Hawkesby said.
"A negative official cash rate is one tool. Other tools include influencing longer term interest rates and you can do that through asset purchases of government bonds or other assets," he said.
"What we're really talking about is contingency planning for an environment where, having used the official cash rate to achieve those goals, we've run out of room to provide more stimulus."
Hawkesby said they've been looking at these methods for a couple of years now for contingency planning.
The Reserve Bank will next consider the official cash rate on 25 March.