The First Minister said a legally-enforceable stay-at-home order will apply from Tuesday to areas currently under the country’s top tier – Level 4 – which encompasses mainland Scotland and Skye.
Exemptions will be in place for carers, essential shopping, unlimited outdoor exercise and being part of an extended household, Ms Sturgeon confirmed.
She stressed that MSPs had to act “quickly and decisively”, describing the country as “four weeks behind London”.
Describing the situation as “extremely serious”, she added: “I can confirm now…that we decided to introduce from tomorrow, for the duration of January, a legal requirement to stay at home except for essential purposes. This is similar to the lockdown of March last year.”
Schools and nurseries will remain closed to most pupils until February, meaning an additional two weeks of home learning for most pupils.
Ms Sturgeon announced the changes in a statement at the Scottish Parliament, which was recalled from recess to discuss stricter measures, telling MSPs taking no action could see Covid-19 capacity in hospitals overrun within “three or four weeks”.
She said: “We have an opportunity in Scotland to avert the situation here deteriorating to that extent but we must act quickly.”
The First Minister said the lockdown decision was taken after a meeting of the Scottish Cabinet on Monday morning.
She admitted that she knew the decisions would not be “welcome” and that they had not been taken lightly.
The SNP leader said the measures were “devastating” and that lockdown would remain in place only if “absolutely necessary”.
The Scottish Government had already announced school holidays were being extended to January 11, with ministers having originally planned for remote learning until January 18.
However, schools will still be open for the children of key workers who cannot work from home, and for vulnerable youngsters.
The First Minister said Scotland recorded 1,905 new coronavirus cases in the past 24 hours, down from the 2,464 reported on Sunday. The daily test positivity rate is 15 per cent – a marginal drop from 15.2 per cent on Sunday.
Currently, the whole of mainland Scotland and Skye is under the toughest tier of restrictions, banning indoor visits except in limited special circumstances and restricting meetings outdoors to six people from two households.
The remaining island areas are in Level 3 and no change was announced from this.
For the rest of Scotland, people will only be allowed to meet one person from another household outdoors from Tuesday, applying to all aged 12 and over.
From Friday, places of worship will close to the public except for weddings or civil partnerships – limited to five people – or funerals, which will be restricted to 20 mourners. Wakes have been banned.
Ski centres, clinics offering cosmetic and aesthetic procedures and showrooms for larger retailers will have to close under a tightening of premises designated as essential retail.
Ms Sturgeon said the lockdown measures will be kept under close review but added: “However, I cannot at this stage rule out having to keep them in place longer, nor making further changes. Nothing about this is easy.”