Brooke Bone, a senior analyst at Milford, said Unleashed provided an innovative software system that added to the strength of cloud applications such as Xero.
"The business is positioned to benefit from the global move to cloud computing. This investment reinforces Milford's commitment to established growth companies with an exciting future," Bone said.
Unleashed was founded by entrepreneur Greg Murphy in December 2009 and now employs about 40 people in its North Shore office.
Some of the firm's employees are shareholders and contributed to the funding round.
Chief executive Gareth Berry said the $4 million investment would allow his firm to expand its operations in Australia, where it currently has five staff in Melbourne and two in Sydney.
Both those offices needed to be "filled" and Berry said he was looking to hire more than a dozen new employees by Christmas.
"Australia is the market we're in predominantly so we need to scale that to ensure we're meeting the demands of the market there," he said.
The other main focus was the US market, where Unleashed planned to open an office in the next 12 months, he said.
The company would most likely be looking to launch from the Kiwi Landing Pad in San Francisco, which many Kiwi tech firms have used to get on their feet in the US.
Unleashed's software can be integrated with other cloud applications and was named as tech darling Xero's add-on partner of the year in 2012.
Most of the company's revenue is being generated offshore but local clients include many of New Zealand's best-known wineries and boutique beer brewers.
