There will be no mixing of two households indoors except for single-person household bubbles and certain other exemptions.
No more than six people from two households can meet in private gardens.
The DUP leader said: “It is in an environment where we feel safe and relaxed that we drop our guard.
“The mixing of households indoors provides one of the best opportunities for the spread of the virus.”
The announcement comes after an unscheduled meeting of the Stormont Executive which was called in response to rising Covid-19 infection rates.
Ministers met at 3.30pm today to consider the further restrictions after two additional deaths and 125 confirmed cases of the virus were announced in the North earlier today.
Professor Ian Young said: “The virus is everywhere and will spread everywhere, and hence our advice is that generalised restrictions are required.
“We believe this is a proportionate response to the increased number of cases, focusing on the settings where most cases seem to be acquired at present.”
He said it had been possible to put in safety measures at hospitality outlets which did not exist in private homes. Pubs which do not serve food will open on Wednesday.
Deputy First Minister Michelle O’Neill said people were “fed up and tired” with Covid-19 but it posed a real threat and they had the opportunity to prevent an even more challenging situation this winter.
“Covid-19 has been allowed to get a foothold in our community and we need to take action now.
“This is a fightback – the months ahead will be difficult.”