The outgoing Sports and Recreation Minister was in Paris for the All Blacks game as one of his last official acts, but it is the legacy of improved women's and girls participation that he says he is most proud of.
The All Blacks lost a dramatic Rugby World Cup final to South Africa on Sunday, going down by just a point at Stade de France.
The Springboks won 12-11 and became the first team to win the World Cup four times.
Robertson was representing the New Zealand government at the game, on a trip approved by Prime Minister Chris Hipkins and endorsed by the incoming Prime Minister, Christopher Luxon.
Robertson said the All Blacks were "absolutely shattered".
"In this occasion I didn't go down and see them, I think in the circumstances they were staying together as a unit as you'd expect and looking after each other," he said.
Robertson said these events were massive diplomatic occasions.
"There were were representatives of the French government, including President (Emmanuel) Macron who I got to speak with briefly, the South African president was there, and people from most other countries that had participated in the World Cup," he said.
"Sport and politics - many people don't want them to ever mix. I happen to think that's a tiny bit naive; they do, and therefore we've got to make the most of these occasions for New Zealand."
Robertson said three women's World Cups were held in New Zealand in his tenure, and he was most proud of the growth in women's sport.
"It's an amazing portfolio... for me it was a really good kind of yang to the yin of finance, which was a massive, massive challenge.
"With a lot of difficult decisions in sport - while there were hugely difficult times through Covid - it was a portfolio where I really felt I was able to make progress," he said.
"I'm particularly proud of our women and girls in sports strategy. To be there at the elite level through three World Cups that we hosted and how successful they were, but also at the grassroots level to see more and more young women getting the opportunity to participate in sport, young women from diverse backgrounds some of whom have never had the chance to participate."
Robertson said one of the lessons for him from the six years of having the portfolio was the importance of keeping the country's grassroots game healthy.
"There is no professional or elite sport without grassroots sport. There's no All Blacks team unless there's a kid dreaming somewhere in rural Taranaki that they want to play for the All Blacks - or for the Black Ferns for that matter."