The Welsh Government has announced the rules are a revised version of alert level two, in a bid to tackle the spread of the Omicron variant.
The measures mean a requirement of 2-metre social distancing where reasonable as well as licensed premises being required to do table service and collecting customer contact details.
In addition, face coverings will also be required in venues, except when seated.
Businesses impacted by the move will be able to access £120m of funding and further details about this will be announced by the Economy Minister tomorrow (Thursday 23 December).
First Minister Mark Drakeford said: “We are facing a very serious situation in Wales. A wave of infections caused by the new, fast-moving and very infectious Omicron variant is headed our way.
“This new form if coronavirus could infect large numbers of people in Wales, disrupting daily lives and businesses and could cause an increase in the number of people who need hospitality care in the coming weeks.
“We will do everything we can to protect people’s health hand livelihoods in Wales – this means taking early action to try and control its spread.
“We are changing the rules for businesses and some public spaces, where lots of different people mix daily and issuing strong and clear advice to help people stay safe in their own private homes and when meeting others.”
Furthermore, large events will not be permitted indoors or outdoors and the maximum number of people who can gather inside will be 30 and outside 50, with the exception of team sports where up to 50 spectators will be able to gather, as well as those taking part. Events involving children will also be an exception.
The restrictions will have a devastating financial impact on firms and could preface early year closures and job losses, despite the cash support, UKHospitality Cymru said.
Executive director for the trade body David Chapman added: "The [measures] virtually close Wales' events industry and take all other hospitality businesses much further into sub-viable trading.
"Hundreds of millions of pounds of business have been lost in the run up to a very quiet Christmas and things will now get worse from Boxing Day.
“Our members are battered and bruised and at the end of their tether. Morale, alongside customer confidence, is low. Our customers have dwindled to a trickle and this news will only make matters worse.”
He went on to note Welsh Ministerial calls for the reintroduced of furlough and said the sort of firepower furlough represented was vitally needed to top up funding help.
Chapman added: “The Welsh Government – like the UK Government – recognises the dismal trading conditions we have had to endure pre-Christmas and has made some more money available today to compensate for losses to date. Welsh Government tells us it has pushed its own financial boundaries as far as it can. The new packages amount to £120m, an additional £60m, but this falls way short of the huge scale of the business that will be lost.
"Cash reserves are long gone; loans are being repaid and costs are soaring. Today’s news here means we need the UK Government to help our businesses in Wales immediately and make more assistance available - and do it quickly. If not, there could be very serious permanent damage done to this industry in just a few weeks."
The Campaign for Real Ale (CAMRA) also called the announcement “devastating news” and outlined the financial impact on businesses.
CAMRA chairman Nik Antona said: “Bringing back the table service only restriction is devastating news and is going to make it difficult, if not impossible, for many of our pubs, social clubs and brewery taprooms to turn a profit.
“Traditional smaller community locals which don’t serve food will be particularly hard hit at a time when the decent Christmas trade they were relying on to help them recover and see them through the quiet months at the start of the year has already evaporated as a result of government announcements.
“Details of the financial support that will be available is now urgently needed. This must include great Welsh breweries, cider producers and the wider supply chain for the beer and pubs sector and must reach businesses as quickly as is possible.
“Any system of grants may help businesses survive the next week or so – but the UK and Welsh Governments must urgently work together bring forward a comprehensive plan to protect our pubs, including a return to furlough, help with rent and extending support with business rates.”
The Night-Time Industries Association (NTIA) called on the UK Government to reimplement furlough and provide further proportionate support to the devolved nations so businesses across the UK can survive.
The Society of Independent Brewers said: "The Welsh Government has brought in the most restrictive measures in the UK, which will severely hit community pubs and small brewers at this critical time of the year. Table service and a reliance on ordering apps particularly harms small brewers as their beers are often hidden away compared to big brands, discouraging consumers from trying local Welsh craft beers.
"The Welsh Government has announced a new £120m package of support and it is vital that small brewers are included in this. The Economy Minister should follow the Scottish model and introduce a Brewers Support Fund that ensures direct and meaningful support to prevent these businesses from going under."