The economic capital has been experiencing a harsh form of confinement since April, with the ban on leaving home in a large part of the city and the isolation of positive cases.
Four of the city's 20 subway lines restarted on Sunday, as did some road transport, forming a "core network covering all central urban areas", according to authorities.
People taking public transport will need to present a negative Covid test less than 48 hours old and have a "normal temperature", they added.
Unlike other major economies, China is pursuing a strict "zero-Covid" policy, consisting of isolating sources of contamination to stop the spread of the virus.
But this approach has proven difficult to hold against the highly transmissible Omicron variant.
With cases declining in Shanghai, authorities appear to be gradually easing restrictions, and some factories have resumed operations.
From May 31, Shanghai will adopt a classification system between "low", "medium" or "high" risk areas, depending on the number of cases found there, a city health official said on Sunday. Zhao Dandan.
People in "low risk" areas will be allowed out of their homes, and "medium" or "high" risk areas will be locked down for 14 days.
The central district of Jing'an was again under a bell on Sunday, and its residents will be subjected to three rounds of tests, according to an official statement.
Restrictions continue in other Chinese cities, including Beijing, which has banned dining out and forced millions of people to work from home.
On Saturday, nearly 5,000 people living in Beijing's Nanxinyuan residential district had been relocated to quarantine hotels after 26 new infections were discovered in recent days, according to state media.
Fears now center on how Beijing will stem the outbreak, and whether it intends to adopt an approach similar to that in Shanghai, where the lockdown has deprived many people of adequate access to medical care and food.
© 2022 AFP