The IsDB has 57 member countries, and is headquartered in the Saudi city of Jeddah. Set up in 1975, it has subscribed capital of $33bn (£23.2bn).
Freud's agency has been working with the organisation since late last year. Last month it supported the inaugural Islamic Finance Summit at the London Stock Exchange, where speakers included UK Government ministers John Glen and Sajid Javid.
In February it helped launch IsDB's Engage, a new platform connecting innovators with market opportunities and funding, which went live at the World Economic Forum in Davos.
Managing partner Ed Amory and Poppy Mitchell-Rose, who was promoted to partner this month, are leading on the account.
The IsDB's new $500m Transform Fund will support science, technology and innovation initiatives that tackle development challenges around the globe.
Alongside Freud himself, its trustee board includes his brother-in-law Richard Curtis, the film director and Comic Relief co-founder with whom he has frequently worked. Save the Children International CEO Helle Thorning-Schmidt is also on the board, while advisors to the fund include government ministers from South Africa and Malaysia.
The fund will work in line with the UN's Sustainable Development Goals, providing seed money for start-ups and SMEs and running in tandem with Engage.
Other large-scale charity and development clients Freud has worked on include Comic Relief, Live Aid, Product (RED), the UN Sustainable Development Goals (in collaboration with Curtis' Project Everyone) and the Bill and Melinda Gates Foundation.
In 2016, Freuds was advising the Saudi royal family on its modernisation programme, PRWeek revealed. Revenue from this, as well as geopolitical work in Dubai, contributed to one of the strongest years in the agency's history.