Ashish Thakkar

LONDON—A divorce-court judge ruled that entrepreneur Ashish Thakkar is the true owner of Mara Group, a private company he founded.

Mr. Thakkar and his wife of five years, Meera Manek, have split and are tussling over his assets. Mr. Thakkar has often been dubbed “Africa’s youngest billionaire” in media articles, though his actual wealth appears far smaller.

Mr. Thakkar had told the court his personal assets are worth less than $600,000 and that Mara Group was owned by his mother and one of his sisters. His wife disputed that, and the judge heard evidence two weeks ago from family members on the company’s ownership structure.

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Justice Philip Moor determined that Mara Group, a holding company for technology, real-estate investments and company stakes, was run solely for Mr. Thakkar’s benefit. The judge didn’t assign any value to the company or indicate how it might be carved up in the divorce.

“He has not been running this business for the sole benefit of his mother and sister. That was a blatant lie,” the judge said in the ruling.

The decision was reached Feb. 10 but made public by the court on Tuesday.

Mr. Thakkar, a British citizen who lives in Dubai, dropped out of school at 15 to sell computer parts across Africa and over 20 years built Mara Group, a holding company whose value isn’t publicly disclosed. Mr. Thakkar, 35, says the “youngest billionaire” description was never accurate.

A Wall Street Journal examination shows that Mara Group has investments and assets worth about $30 million.

Mr. Thakkar and Ms. Manek separated in 2013. They don’t have any children.

Last month, the Journal reported on a series of setbacks for Mr. Thakkar and Mara Group, including problems raising financing for some of its projects and questions by investors over the group’s size and scope.

Mr. Thakkar regularly says Mara Group employs 11,000 people in 25 countries. The figures include companies where Mara Group or Mr.Thakkar hold minority stakes or board seats, such as at Atlas Mara Ltd., the African banking group he co-founded with former Barclays PLC Chief Executive Bob Diamond. Mr. Thakkar has a 0.3% share of the company.

Asked by Justice Moor during the hearing why he wan’t entitled to an ownership stake in Mara, Mr. Thakkar said: “I’ve never been motivated by the wealth factor.”