Travellers from Denmark must self-isolate after widespread outbreaks of Covid-19 in its mink farms.
Nicola Sturgeon announced the move at the Scottish Government's coronavirus briefing on Friday, minutes before it came into effect at 12.30pm.
It means anyone travelling to Scotland from Denmark will have to self-isolate for 14 days on arrival.
Sturgeon said: "Health authorities in Denmark have reported cases in humans of a variant strain of the virus associated with outbreaks in mink farms.
"We've taken this decision on a precautionary basis but it is important that we do so. The UK Government announced a similar move last night.
"The Danish authorities are working very hard to contain this situation but of course we will continue to consider whether there is a need for any further protections.
"The UK chief medical officers will consider updated information later today to assess whether any additional action beyond quarantine may be required."
Scotland's chief medical officer Gregor Smith said action is required to safeguard public health.
He added: "If anyone has any concerns, as in any case, whether or not they have travelled from Denmark, they should follow the guidance laid out by Scottish Government and if needed contact NHS 24."
The move comes after the Scottish Government announced on Thursday evening that arrivals from Sweden and Germany will be placed on the quarantine list from 4am on Saturday.
Meanwhile, Sturgeon told the briefing Scotland recorded 31 deaths from coronavirus and 1,072 positive tests in the past 24 hours.
The death toll under this measure - of people who first tested positive for the virus within the previous 28 days - has risen to 2,997.
The daily test positivity rate fell to 5.5% from 7.6% on Thursday.
Of the new cases, 460 are in Greater Glasgow and Clyde, 210 in Lanarkshire, 112 in Lothian, and 75 in Ayrshire and Arran.
There are 1,237 people in hospital confirmed to have the virus, down by 15 in 24 hours. Of these patients, 98 are in intensive care, up by three.
Sturgeon also announced an additional £1.3 million to improve mental health and wellbeing support for students.
The cash will allow colleges and universities to enhance current provision and could be used to expand counselling services, deliver more support online or improve their ability to check on the welfare of students.
The First Minister said: "We know that students have faced some particular pressures since the start of the new academic term, many of them will be away from home for the first time, which is always a difficult adjustment for young people to make, but in addition to that they are having to adapt to new forms of learning and socialising, and of course many students have also had to deal with the challenges of self-isolation."
She said the cash should "help all students get the right support whenever they need it".
