The ITV Studios production will air in the autumn and feature Joly, star of Channel 4's 'Trigger Happy TV', poking fun at what it means to be British through a range of new characters and pranks.
The sponsorship, which was negotiated by MediaCom, will include broadcast, online and mobile elements and the idents will be made by TBWA/London.
The show marks the first time ITV has commissioned a full show with Joly, who came fourth in the 2010 series of 'I'm a Celebrity… Get Me Out of Here' and has appeared on ITV2 panel shows.
Lesley Stonier, senior brand manager for Aquafresh, said: "The sponsorship is a great brand fit for Aquafresh due to our reputation as great-tasting toothpaste enjoyed by all the family and our iconic red, white and blue stripes delivering a true sense of Britishness.
"It also offers the perfect, primetime platform for us to connect with our target audience and we are proud to be partnering with 'Fool Britannia' to deliver a taste of British family fun to the nation on a Saturday night."
'Fool Britannia' will be part of ITV1’s Saturday night schedule, alongside ‘The X Factor’, which began this weekend with its lowest opening audience in six years.
GSK appointed TBWA Worldwide to handle its estimated £100m Aquafresh global advertising account in February and the business is led by TBWA/London.Follow @MaisieMcCabe