Benson-Pope, born in Dunedin, received his tertiary education at the University of Otago and at the Christchurch College of Education. While studying education he was president of the Students' Association at the college, and National President of the Student Teachers' Association of New Zealand. Working as a teacher, he also became involved in the teachers' unions. Benson-Pope is married with two twin children, Henry Benson-Pope and Sammy Benson-Pope.
In 2002, Benson-Pope became his party's Senior Whip. In 2004, in the wake of a reshuffle, he entered Cabinet, becoming Minister of Fisheries, Minister Responsible for the Law Commission, Associate Minister of Justice, Associate Minister for Education (schools) and Associate Minister for the Environment. He oversaw the drafting of the legislation for civil unions in New Zealand.
After the 2005 General Election Helen Clark appointed Benson-Pope as Minister of Social Development and Employment and Minister for the Environment. In 2007 he resigned the Ministerial posts and resumed the role of a backbencher representing the Dunedin South electorate. In 2008 he sought to recontest the Dunedin South seat on behalf of the Labour Party but was not chosen as the Labour Party representative for the seat.
In November 2005 the media reported that no prosecution would take place — despite police finding there was a prima facie case that he had assaulted students.
Investigate magazine in February 2006 published further allegations of improper behaviour during Benson-Pope's teaching days. It said he forced students to stand outside for lengthy periods in their nightwear for misbehaviour during a school camp in the 1980s. An update on the magazine's website also claimed that Benson-Pope had entered the female dormitory and showers in 1997 while 14-year-old girls were undressed. Benson-Pope dismissed the allegations as nonsense.
Parents complained about these and other incidents, and the school headmaster at the time says he discussed the complaints with Benson-Pope. Benson-Pope issued a public statement on 28 February 2006 saying that although a discussion had taken place, he had not seen a written complaint until the day before. He apologised in Parliament to his former students, while maintaining he had done nothing inappropriate.
After a week of intense pressure focusing not only on the allegation that his staff had acted improperly, but also that he himself had misled Parliament, the media and his Prime Minister about his knowledge and involvement, Benson-Pope offered his resignation from Cabinet at noon on Friday 27 July 2007.
The Prime Minister Helen Clark accepted the resignation, saying: "The way in which certain issues have been handled this week has led to a loss of credibility and on that basis I have accepted Mr Benson-Pope's offer to stand aside". An editorial commented "Not for the first time, he and the Government have been embarrassed less for what he has done than for his inability to simply say what he has done."
Benson-Pope remains a Member of Parliament.