The cup was among several items (some are pictured) taken during a raid at All Saints Church on Old Church Road in Chingford overnight between 21st and 22nd November 2018.
PC Nicole Garcia, said: "These items are of great importance to the church and its congregation.
"I would urge anyone who has been offered them for sale to contact us. They are quite distinctive and would have stood out.
"The idea that someone would break into a place of worship is cause for concern and I would encourage anyone with information to come forward."
The chalice has a watermark dating to 1595 and has an estimated worth of £20,000.
Rev Andy Trenier was quoted by the Evening Standard newspaper as saying: "It's more than sentimental; it's a piece of the parish that has been stolen.
The suspect(s) gained access via a window before stealing a collection of items including chalices and a ciborium. https://t.co/wNXXUQtzdS
— Metropolitan Police (@metpoliceuk) February 8, 2019
"It's totally irreplaceable. It's quite plain with worn silver and a rose stem pattern."
Three locked doors were smashed through in order to gain access to a safe housing the chalice. Other stolen items include a chatten, a flaggon and a ciborium.
Anyone with information is asked to contact officers at the North-East Command Unit via 101 quoting reference 2174/22Nov18.
Alternatively, they can call Crimestoppers anonymously on 0800 555 111.
There have been no arrests. Enquiries continue.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.