Social Development Minister Paula Bennett said an extra $17.2 million was being invested to pay for them because of rising unemployment.
"Work and Income agreed it could manage numbers on the unemployment benefit up to 60,000," she said.
"However, as that figure grows closer, extra staff will be required."
Ms Bennett said the number of people on the dole was over 50,000 for the first time since 2005.
"Today's announcement means the right resources can be deployed right now to the right areas," she said.
"It's important that help is provided upfront so as many people as possible can get work and avoid having to go on a benefit."
Of the 303 extra staff, 104 have already been recruited to work in the Auckland area.
Ms Bennett said the department had lifted its game and was finding jobs for people.
"Its vacancy numbers are actually more than 50 percent higher than for this time last year - despite growing unemployment," she said.
Speaking at a press conference in Auckland, Ms Bennett said she was asking more of her staff.
"I'm asking them to look wider at the job market. I'm asking them to do skill matches and where the person can go into," she said.
Work and Income's regional commissioner for social development, Isabel Evans, said that with the extra staff the department would be on the front foot all the time.
"But I can't stress enough - we have to have the jobs there for our clients," she said.
"Widening and broadening the number of employers we have working with us, talking to us when they do have any recruitment needs, is equally as important as working intensively and more closely with our clients."
Statistics issued yesterday showed the unemployment rate had increased to 6 percent and the number of people without jobs was at a 10-year high of 138,000.
