The phased reopening of the Bronze Age site will see the parkland open first, with the visitor centre and gift shop available to browse. Limited takeaway food will be offered, and restrooms will be safe to use.
The house, artefacts and exhibitions will remain closed for the time being, as guidance doesn't yet permit them reopening.
From April 12, the opening times will be daily from 10am to 4pm - including on weekends.
A new walking trail will be launched for 2021, featuring fun family activities like spotting wildlife in the area. The trail leaflet can be picked up at the entrance to Flag Fen, or downloaded via a QR code at the site.
Walkers are reminded that dogs are not permitted due to the large number of sheep on the parkland, but owners with assistance dogs are welcome.
Cyclists looking for a stop-off on the city’s Green Wheel cycle route, which runs past the front of Flag Fen, are also welcome and can use bike racks at the attraction.
Hand sanitiser and washing stations will be at the entrance to use, and Track and Trace is in place.
City Culture Peterborough took over the running of the historic site when Vivacity terminated its contract with the city council last summer.
Sarah Wilson, heritage and arts programming manager at City Culture Peterborough, said: "Flag Fen has been closed for a year and we know people have missed visiting. There’s a focus now more than ever before on the benefits of exercise in green open spaces. The parklands that surround the attraction are perfect for a good walk.
"We’ve taken every careful step to ensure Flag Fen is safe for people to visit, which includes adjusting our opening times and managing the number of people simultaneously permitted to be inside the main building.
"I strongly encourage anyone to visit and enjoy what Flag Fen has to offer and to find out about what we have in store in the coming months. For example, while restrictions remain, we are planning free online talks by archaeologists on some amazing objects and exciting discoveries from sites across the country."
Back in October, a fire was set at the attraction, but the organisation confirmed that no damage was done to any of the artefacts.