The 19-strong team from Defaqto, a financial information business based at Haddenham Business Park are joining 1,200 people from more than 100 businesses.
Each member of the company's staff who is participating is aiming to raise Â£400 each.
So far between them staff have raised Â£2,700 and in total they are aiming to raise Â£7,000.
One of the fundraising events was dressing up on a Halloween theme for the day (photo above).
The company's chief financial officer Alastair Brown said: "I came across this sleep-out event in London and decided it was something I wanted to be involved in.
"We are having a lot of fundraising events in our office over the next few weeks - a cake sale, a quiz and a raffle to name just a few."
Mr Brown said although the event was likely to be a lot of fun, there was a serious reason behind it.
He said: "We are not trying to replicate homeless, just raise awareness of it and money for the charity Centrepoint, which aims to give homeless young people a future.
"We are looking forward though to find out who the loudest snorer in our team is!"
The sleep out event takes place at the Greenwich Peninsula on Thursday November 15.
If you would like to donate to the company's cause please visit www.sleep-outlondon2018.everydayhero.com/uk/mike-2