The southern African country’s national disaster management agency said 77 people had been rescued.
Zimbabwe’s Civil Protection Unit (CPU) said in a statement that 114 adult passengers were on board, which it said was confirmed through ticket sales, along with five crew members.
There may also have been an unknown number of children below the age at which tickets are needed.
The boat has a carrying capacity of 90 people, the agency said.
Earlier, Zimbabwe police said the boat had 90 people on board when it capsized on the lake, which lies on the border with Zambia.
Those pulled out of the water by rescue teams and others, have been taken to Long Island, an island inside the lake on Zimbabwe’s northern border.
From there, they are being brought to land on CPU vessels.
Zimbabwean state broadcaster ZBC published video of speedboats making their way to what appeared to be an overturned boat on the lake as a helicopter hovered overhead.
