Unitec's council was replaced last month by a commissioner, Murray Strong, who has also been appointed Crown manager of another troubled polytechnic, Greymouth-based Tai Poutini.
Hipkins said an independent financial adviser was appointed to Whitireia last month.
"Whitireia will require $15m in 2018 to meet its cash shortfall and operating costs. Further support may be required in 2019 unless urgent action is taken," he said.
"Current students can be assured that they can complete their courses and future students should have the confidence to enrol."
He said that while Unitec and Whitireia both have unique issues, they are not alone in facing the effects of falling student numbers.
"This situation shows the absolute need for the work now being done under the Institutes of Technology and Polytechnics Roadmap 2020 to secure a viable future for the institutes of technology and polytechnics sector across New Zealand," he said.
"We need a strong polytechnic sector that delivers what New Zealand's learners and employers need from it in a rapidly changing world, and at an affordable cost to taxpayers."