Mthethwa won against rivals Nompumelelo Javu of the Eastern Cape and Kgapane Rrabotho of Gauteng central.
"It's back to the drawing board now. We have a lot of plans and ideas that we want to implement as soon as possible," said Mthethwa.
"Elections were not a worry to us, we want to serve those who support us. We have a passion for netball and our country, and that is what makes us proud to be on the executive."
Also retaining her post is vice-president Blanche De La Guerre of Gauteng North.
"The people and the council showed their confidence in us as leaders and we will not disappoint them," said De La Guerre.
"Our focus now is on club and technical development, as well as building relationships within schools netball."