"It's a bit sad to be giving up as a councillor but at the same time I am pretty excited with my new job, and being able to work fulltime," she said.
Ms Robertson became the youngest councillor at the council table when she was elected aged 26 in 2007.
She went to council principally as an advocate for younger people and brought to the table a firm understanding of issues involving Featherston, in particular, as she had lived all her life in the town.
Ms Robertson is a firm friend of South Wairarapa mayor Adrienne Staples, the two sharing a love of horses and horse riding.
Mrs Staples has already announced she will not be seeking another term as mayor, after 12 years' service in the top elected role.
"We will both be riding off into the sunset," Ms Robertson said.