Dame Diane Robertson, DNZM, was born in Waipukurau in 1953. She was educated at Tararua College and then studied at Palmerston North Teachers' College, where she gained a Diploma of Teaching.

In 1998, Robertson was appointed the Auckland City Missioner, having previously been a teacher, counsellor and involved in youth work and a manager of a social services agency. She was the first woman and the first non-cleric to hold the role.

In September 2015, she announced that she would step down from that post at the end of 2015. Robertson is chair of the Data Futures Partnership, chair of the Goodman Fielder Cares Foundation and a member of the Vulnerable Children's Board.