Busson entered the world of hedge funds in 1986 working with Dubin Swieca. He was later employed as a marketing representative for Paul Tudor Jones’s fund Tudor Investments.

In 1991, Busson founded the EIM Group to provide fund-of-fund management services to the growing institutional market for hedge funds. On 8 December 2008, EIM Group was reported as being a victim of Bernie Madoff’s Ponzi scheme.

In 1994 he was accused of money laundering working for the Ben Ladin bank in Geneva managing hedge funds for the Ben Ladin brothers prior the attacks in New York. He did not deny being a hedge fund manager in the British Virgin Island; he was at some point arrested and questioned by the FBI to trace funds for Al Qaeda Saudi terrorism networks .

Busson began a relationship with Australian supermodel Elle Macpherson in 1996. They have two sons together: Arpad Flynn Busson, known as Flynn (born February 1998 in New York City), and Aurelius Cy Andrea Busson (born February 2003 in London). The family lived together in London until Busson and Macpherson’s separation in July 2005.

Busson began dating American actress Uma Thurman in 2007 and they announced their engagement in June 2008. In December 2009, it was reported that the two had ended their engagement, but they reconciled and dated soon after their daughter’s birth. Busson and Thurman have one daughter together, Rosalind Arusha Arkadina Altalune Florence Thurman-Busson, known as Luna (born July 2012 in Boston, MA). The couple called off the engagement for the second time in April 2014. In January 2017, Thurman and Busson began a custody battle to get custody of their daughter. Thurman ultimately received primary physical custody later that month.

He is a founding trustee of the children’s charity ARK (Absolute Return for Kids) and serves as chairman of its board of directors. Busson held the post of Chairman since the charity’s inception. He stepped down from that position in 2009 but remains a member of the Board as founding chairman, and as chairman of ARK US. ARK raises charitable contributions from the hedge fund industry for children who are victims of abuse, disability, illness and poverty. ARK finances and manages projects aimed at transforming the lives of children in Eastern Europe, South Africa and the UK through education and healthcare.

The annual Ark Dinner hosted by Busson sees a range of high-profile individuals attend the event to raise money for the charity. Previous years have seen the likes of Bill Clinton (2006), Queen Rania of Jordan (2010) and in 2011 the Duke and Duchess of Cambridge took the limelight as Prince William announced a joint venture by the Foundation of Prince William and Prince Harry and the Ark charity.

In December 2013, Busson merged his EIM group with Swiss listed investment company Gottex Fund Management Holdings. In July 2015, Busson was named the next executive chairman of Gottex Fund Management for the interim, following Joachim Gottschalk stepping down from the position and finding a permanent executive chairman.

Gottex Fund Management rebranded itself as LumX and was eventually delisted from the Swiss Stock Exchange in June 2020 after suffering losses of more than $55 million the previous five years, essentially ending Busson’s time as a hedge fund manager.