The Us team, consisting of the former Saatchi & Saatchi creatives Joe Tanner and Mark Howard, have worked on the account since the business was conceived in mid-2005.
M&C Saatchi was brought in later in the process and will now assist Chariot with the launch of a £10 million integrated campaign to introduce the new lottery game this summer.
Goodstuff will handle the media strategy on the launch, M2M will cover media buying and Grasshopper will run below-the-line marketing.
Andrew Williams, the marketing director of Chariot UK and former head of brands at Prudential, said: "We have created a virtual agency with a team of different talents driving the launch. Richard Alford at M&C Saatchi will oversee the launch from an account management point of view, working alongside Us, which will handle creative duties."
Chariot UK, which will be floated on AIM next week, is a new weekly alternative to the National Lottery.
It is a classic lottery game where players choose six numbers from a possible 49. However, the main prizes will be smaller than the National Lottery's and there will be higher prizes for matching three, four and five numbers. The odds of winning a prize will also be better.
The company is promising that 30p from every £1 spent will go directly to one of the company's 50 affiliated charities, which include Shelter, the British Heart Foundation and War Child.
Chariot is aiming to partner a further 20 charities by the time it launches.
The funding given to the charities is also unrestricted, which means they can use it for any purpose.
Williams said: "If we reach our targets,we will be able to raise £150 million every year for the charities."