For the event, Duchess Catherine wore a striking cobalt blue dress by Eponine. It featured three-quarter length sleeves and was clinched at the waist with button detailing.
She added a pair of navy heels and wore her hair in a slick up-do.
The event comes as the conference ramps up with world leaders expected to reconsider and even rejig legislation in order to come up with effective climate change solutions in their countries.
A big part of this year's conference is a push for countries to enact a goal of achieving net zero carbon emissions by 2030.
Of course, all eyes are also on Australia and its Prime Minister Scott Morrison at the conference given the country is one of the world's biggest polluters per capita.
But worryingly, Morrison announced last week the country's intention to achieve that target 20 years after the projected timeline—in 2050.
As for the 2030 target, Morrison is forecasting to cut up to 35 per cent of carbon emissions based on 2005 levels. At the conference, he told world leaders that he expects to "exceed" that target.