Former mayor Garry Daniell was not present; he told the Times-Age he was not aware the event was on yesterday.
Mrs Patterson congratulated both new and returning councillors on their success in the recent elections.
"We are a new team, with new leadership.
"Like many rural districts we face challenges, but we also have opportunities to build a more progressive and inclusive district - a district where we value our people, our environment and one another.
"For this triennium council will lead, support and advocate whenever, or wherever, necessary to grasp those opportunities to take our district forward."
Mrs Patterson said council would work closely with the community to prioritise its work programme.
"This district, with its proud history, has an exciting future. Let us all work together to ensure that Masterton prospers so that all that live here will benefit from it.
"Let us roll up our sleeves and get on with it," she said.
Mrs Patterson formally declared rural ward councillor Graham McClymont as deputy mayor.
"I'm thrilled that he's accepted the position, I think we are a good balance for one another."
Mr McClymont said he had been surprised but was looking forward to the challenge.
"You have my total support and the support of the councillors in front of you.
"I hope between the two of us that we can take Masterton forward, I wish you all the best," Mr McClymont said.