"We now need to take action because we cannot have the confidence as a group of leaders that the social distancing guidelines and rules that we have put in place won't be followed to the level of compliance that we require to flatten the curve and slow the spread and save lives," Mr Morrison said.
"This should highlight to all Australians how serious this is and how hard we all have to work together to get this right."
New South Wales, Victoria, and the ACT had earlier announced plans to shut all non-essential services over the next two days, but the agreed national measures did not go that far.
All states and territories instead agreed to shut: licensed sections of pubs and hotels, clubs, cinemas, casinos, entertainment venues, indoor sporting venues and indoor places of worship.
Restaurants and cafes will be restricted to takeaway services only.
Mr Morrison said while schools should remain open, parents can choose to keep their children at home if they wish.
He also said there was “no need” for anyone to flood supermarkets or rush to any place that would close at midday on Monday.
“What we're doing is closing down gatherings in pubs and clubs and things of that nature," Mr Morrison said.
“There is also no reason for anyone to rush to any of those venues tomorrow before midday. That would be highly irresponsible.
“I would just simply ask Australians to get a hold of themselves if they were thinking of doing something of that nature.”
Coronavirus symptoms can range from mild illness to pneumonia, according to the Federal Government's website, and can include a fever, coughing, sore throat, fatigue and shortness of breath.
As of Sunday morning, only people who have recently travelled from overseas or have been in contact with a confirmed COVID-19 case and experienced symptoms within 14 days are advised to be tested.
If you believe you may have contracted the virus, call your doctor, don’t visit, or contact the national Coronavirus Health Information Hotline on 1800 020 080.
If you are struggling to breathe or experiencing a medical emergency, call 000.
Additional reporting by Rosemary Bolger and Evan Young.