Currently, Chesterfield, North East Derbyshire, Erewash and parts of the High Peak are in Tier 2.
The rest of the county – Amber Valley, Bolsover, Derbyshire Dales, all of the High Peak, South Derbyshire and Derby county – will be placed in Tier 2 from 12.01am on Saturday.
The Government confirmed the change following talks with local leaders after a recent upsurge in Covid-19 cases in the county.
As a result of the change, people will no longer be allowed to mix indoors with others unless they are from the same household or form part of a support bubble.
Some early reaction has come in.
Councillor Barry Lewis, leader of Derbyshire County Council, said: “Please adhere to the guidance and help keep us out of Tier 3.”
Mark Fletcher, Bolsover MP, added: “This action is needed now and we must all work together."