According to reports, the 44-year-old mogul was walking into the Colosseum Hotel and Fitness Club in Oyster Bay, Dar es Salaam for his routine gym session during the early hours of Thursday morning when two white men and an unknown number of accomplices in two cars waylaid him and quickly drove away.
Three people have been arrested in connection with the kidnapping and two are believed to be foreign nationals, police said.
METL is active in textile manufacturing, flour milling, beverages and edible oils in eastern, southern and central Africa.
Dewji is also the first Tanzanian to join the Giving Pledge, a commitment by billionaires to help address society's most pressing problems by promising to give more than half their wealth to charity.
"I've spoken to his father and the news of the kidnap of our friend Mo is true", State Minister for Environment and Union Affairs January Makamba said on Twitter.
In his day to day life he didn't look like a billionaire - he was a friendly, affable young man going about his business. He served as an MP from 2005 to 2015. "Mohammed has a family and young children".
Businessmen have never felt at risk of being kidnapped and they often move around on their own. "They shot in the air once and the hotel's security guards scampered for safety", the driver said.