"[Mr Sibery] understands community engagement and will enjoy the environment that Kaipara provides," Mr Robertson said.
Meanwhile, the KDC commissioners were pursuing former chief executive Jack McKerchar through the Employment Relations Authority for his handling of a botched sewerage system initially estimated to cost $10.8 million, but which ended up costing five times as much, leading to spiralling debt.
Mr McKerchar left the council in 2011.
Mr Robertson said the recruitment campaign to find Mr Sibery had been "extensive" and his starting would coincide with the new council due to be elected October.
Mr Sibery - who holds a Master of Arts in Modern History from Oxford University and a PHD in international studies from the University of South Carolina - said in a statement he was looking forward "immensely" to moving to Kaipara and meeting the district's people.
"It is a rich and diverse area that I always enjoyed visiting ... There is great potential here and I am keen to work with everyone involved to ensure that we are successful and competitive."
Mr Sibery replaces acting chief executive Dr Jill McPherson.