Miss Mullins said there had been strong interest, via Central Bay Softball's Facebook page, from potential senior teams.
Schools, pre-schools and sports clubs are being approached this week and the doors will be opened to teams from outside of Rotorua including the likes of Reporoa and Taupo, South Waikato and Kawerau.
Registration nights are being held tonight and tomorrow from 4pm until 7pm at Puketawhero Park on Vaughan Rd.
Before moving to Rotorua Miss Mullins was involved with the Waitakere Bears Softball Club, helping to rebuild it when it was in danger of folding. It is now one of the biggest and strongest clubs in New Zealand.
All four of Miss Mullins' children play the sport at representative level and when three months ago she was told there was currently no active Rotorua softball league she set about to re-establish the sport.
"I decided to bring the game back to Rotorua and surrounding areas - we have a lot of raw talent here," she said.
"Council has provided us with Puketawhero Park for training and Saturday games - this is an exciting venture and we also have the backing of Softball NZ."
She said it was important to include children's grades to help build a strong future.
"The kids are the future of the sport and getting their interest from a young age will help to ensure softball has a good future here in Rotorua," Miss Mullins said.
She is also keen to get softball played at schools around the district through running tournaments and introducing representative teams.
Rotorua district councillor Charles Sturt, who heads the council's sport and recreation portfolio, said he was rapt to hear softball would be returning to the district.
"We had a great softball community here some years ago and it's great that someone has taken up the challenge to get things going again - it only takes one person with drive to motivate others so well done to those involved.
"Sharing a venue with another sport, in this case rugby league, is exactly the sort of partnership we need in Rotorua to ensure we have a strong sports base year-round and maximise the use of our sporting facilities," Mr Sturt said.