"Next year they'll go back to [separate] Taranaki, but this year it was just easier to have them with us," O'Keefe said.
"It's because I'm such a great organiser," she laughed.
O'Keefe said they are hoping for another good turnout this evening, with the Royal Opera House being a much larger venue than Collegiate.
"We've just got bigger and better.
"We normally have an amazing amount of support from Whanganui."
From her Revitalise gym, the locals taking part are Daniel Foulkes, Micheala Sullenburger, Maureen Thomas, Ali Richards, and Shelby Moir.
Both Richards and Thomas have had great success at the NABBA national championships.
Tim Warren and one other women's competitor have signed up from City Gym, while Inspire will be represented by Mark Kaipo and Kirsty Harvey.
"I think Whanganui is going to take the whole show," said O'Keefe.
"The Whanganui guys have a really good chance of doing well."
All competitor totals will be combined to find the prestigious Top Gym winner, which is currently held by Snap Fitness in Palmerston North.
Rangitikei Active Gym in Marton claimed the prize back-to-back in 2014-15, while City Fitness held it in 2013.
The judging round for the titles will start at 12pm, when the competitors will do their hardest routinees, which will be followed by the evening show at 6pm, which is more about performance for the audience
"As a competitor, even though they've been judged already, they still giving it 110 per cent because of the fans," O'Keefe said.