"With a slowing economy, China is looking at all sorts of levers to pull to support it, and a weaker currency is certainly one of those levers," Shareef said.
Khoon Goh, a Singapore-based strategist at Australia & New Zealand Banking Group, told Bloomberg: "It looks like this is the end of the fixing as we know it.
"The one-off devaluation of the fix and allowing more market-based determination takes us into a new currency regime."
Analysts linked the move to China's attempts to add the yuan to the benchmark currency basket, which would give the country Special Drawing Rights - the ability to borrow from the International Monetary Fund (IMF).
The IMF this month said it would delay any move to add the yuan to its benchmark currency basket until after September 2016.
China had to balance the need to boost exports with the risk of a cash exodus, Tom Orlik, chief Asia economist at Bloomberg Intelligence, said in a research note.
He estimated a 1 per cent depreciation in the real effective exchange rate boosted export growth by 1 percentage point, with a lag of three months. At the same time, a 1 per cent drop against the US dollar triggered about US$40 billion in capital outflows, he said.
"The risk is that depreciation triggers capital flight, dealing a blow to the stability of China's financial system."
Data over the weekend showed China's overseas sales fell 8.3 per cent from a year earlier in US dollar terms in July, well below the estimate for a 1.5 per cent decline in a Bloomberg survey.