The online platform offers the chance to win "dream-come-true experiences", such as meeting celebrities and luxury trips, with about 60 per cent of the proceeds going to the charitable causes, according to Omaze.
It has worked with celebrities including George and Amal Clooney, Chris Hemsworth, Daniel Craig, Idris Elba and Emilia Clarke, raising more than $161m. The UK will be the California-based platform's first market outside the US.
The UK launch will feature a prize draw campaign on behalf of the Royal Manchester Children's Hospital Charity.
Olley Goss PR's corporate and consumer brief includes establishing Omaze as the leading social-enterprise fundraising platform in the UK and beyond.
The aim of the launch campaign is to drive ticket sales and build the brand's profile, reputation and influence in the UK.
"Olley Goss understand that Omaze represents the future of fundraising – it democratises giving and offers entrants a fantastic chance of winning out-of-this-world prizes while making a hugely meaningful contribution to charities," said James Oakes, SVP International at Omaze.
Olley Goss PR co-founder Andrew Olley said: "[This] is a major year for expanding the Omaze brand globally – beginning with the UK – so that charities can reach bigger audiences to raise not only more money, but also awareness for good causes."
Olley Goss, which launched last year, works with tech brand DataSparQ, British Nigerian artist Yinka Shonibare, real tennis world champion Rob Fahey and emerging wellbeing brand Clearly CBD. The agency was chosen as one of PRWeek's 11 new agencies to watch in 2020.