The twin-tower suspension bridge stands 141 metres (463 feet) above Maputo Bay, is 680 metres-long and joins the city centre to the outlying district of Katembe.
"Today is a unique day of our history, the achievement of the dream of (former president) Samora Machel," Nyusi said at a rally following the inauguration.
"With the completion of this bridge... the connection of southern Africa to the north over land and across our country is guaranteed."
The bridge, which connects the north and south banks of Maputo that were previously linked only by boat, would help promote tourism, Nyusi said.
It will also directly link the capital to the border of neighbouring South Africa by road for the first time.
Ninety-five per cent of the bridge's cost was financed through loans provided by Chinese lenders.
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