In 2008, Nantomah began his career in project management. Three years later, in 2011, he founded a project management training program in Lagos where he trained over 3,000 bankers from various institutions across Nigeria, excluding Zenith Bank, which had its own training structure at the time.[1][3][4]
In 2016, Nantomah and his family moved to the United States where he started to invest in real estate. He served as a campaign staff member for Scott Walker, the then governor of Wisconsin, and was also a member of the national planning committee for Tony Evers, the incumbent governor of Wisconsin. In September 2020, Nantomah was recognized by the 45th President of the United States Donald Trump with the President’s Honours Roll.[5]
On August 6, 2025, the United States Securities and Exchange Commission charged Joseph Nantomah and his three Wisconsin based companies with operating a real estate-related offering fraud, targeting members of the Nigerian-American community.[9]