"Electron is orbital. Successful payload deployment," the company tweeted.
The Electron rocket, named "Still Testing", took off from Mahia, on the east coast of the North Island, at 2.45pm (0145 GMT) on Sunday and reached orbit eight minutes later.
The 17-metre-long (55ft 7in) carbon-fibre rocket is carrying three satellites into space -- one to take images of Earth for United States company Planet Labs, and two to capture weather and ship tracking data for Spire Global.
"Speechless. Just like that, @rocketlab reaches orbit and sets a new bar for launch by reaching orbit on just their 2nd test," satellite-powered data company Spire tweeted.
Rocket Lab conducted its first launch last May when the firm put a rocket into space, but it did not reach orbit.
Backers include US companies Khosla Ventures, Bessemer Venture Partners, Lockheed Martin, Promus Ventures and Data Collective.
The company says its mission is to provide "frequent launch opportunities to low Earth orbit" with a range of rocket systems and technologies "for fast and affordable payload deployment".
Rocket Lab launch services with Electron are reported to cost US$4.9 million per flight.
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