There are 48 regional community foundations across the UK, which together gave out 20,000 mainly small grants to local causes, worth a combined total of £62m in 2013/14.
French, a City lawyer by background, joined Marie Curie in 2009 and is a trustee of three charities including Goodenough College, which provides accommodation for postgraduate students in London.
He will takes up the new role in March, and said in a statement: "I am convinced that community foundations have a critical role in today's society and have massive potential to grow their funding and influence."
French replaces Stephen Hammersley, who left UKCF in December after 10 years in the role.
Kate Stewart, partnerships director at UKCF, will be interim chief executive until French joins.
As reported by Third Sector in the January edition of the magazine, Marie Curie has appointed Jude Bridge, formerly global brand director at the retailer Mothercare, to lead a new directorate encompassing marketing, fundraising, communications, policy and public affairs.
Nobody from UKCF was immediately available to provide details of French’s salary package. The charity’s annual report for 2013/14 shows its highest earner was paid between £60,000 and £70,000.