Only 21 women work in a group of almost 1,000 part-time firefighters.
Recruits from ethnic minority communities are also in demand, a fire service spokeswoman said.
Chris Kerr, chief fire officer, said part-timers made up more than half the total number of firefighters across 37 stations in Northern Ireland.
"Northern Ireland Fire and Rescue Service (NIFRS) could not operate without our retained firefighters as they provide the emergency fire and rescue services to the communities in which they live and work," he said.
The service employs 895 full-time firefighters, of whom 27 are female, and 955 part-time, of whom 21 are women. It is anticipated the new posts will be appointed by October.
Mr Kerr added: "It is an extremely rewarding and interesting job and retained firefighters must be able to quickly respond to emergency call outs by making their way to their local fire station within five minutes."