Dame Elizabeth Hanan received the honour at the festival's annual meeting in Dunedin last week.
It recognised her contribution to the festival since its inception in 1997.
Festival president Mike Harte described her as influential and noted her "amazing leadership".
"With her continued commitment and support, we are now getting ready to celebrate the seventh festival. If anyone should be a life member, she should."
Dame Elizabeth was taken aback by the award.
"I had no idea it was in the pipeline and am thrilled to be the first recipient," she said.
Receiving the award will not change her role, though.
She will continue to provide support, governance and ideas for the festival which made Dunedin "buzz" and was an example of a "good gown and town partnership".
She was pleased with the success of the festival and was "extremely proud" to be part of an event which showcased science excellence.
The life membership award joins a substantial list of others bestowed upon Dame Elizabeth.
In 2003, she became a Companion of the Royal Society of New Zealand for her contribution to science communication, and in 1998 she was made a dame for services to the community.
The next New Zealand International Science Festival will be held between July 6 and 11.
