Until the decision, Sunday's (AEDT) contest in Cardiff was the only match in round five of the tournament still scheduled to take place this weekend.
The Italy v England and France v Ireland clashes had previously been postponed due to the COVID-19 pandemic and an announcement on Saturday (AEDT) from the Welsh Rugby Union confirmed its game would also not go ahead as planned.
"The Welsh Rugby Union has maintained an open dialogue with, and continued to seek advice and direction from, the National Assembly for Wales and other stakeholders, including the Six Nations, on this fast-moving issue," read a statement, which was published 24 hours before kick-off.
"Whilst medical advice remains consistent, we have decided that it is in the best interests of supporters, players and staff to fall in line with recent measures taken across the UK and global sports industries.
"The WRU would like to thank all parties for their counsel on the subject and will make further announcements with respect to rescheduling the fixture in the coming days.
"Every effort has been made to stage this game and we appreciate that individuals will have been inconvenienced. Given the fluid and unprecedented nature of this issue a postponement became the only viable option."
The WRU had earlier said the game was still on, but the landscape changed when a host of other high-profile sporting fixtures for this weekend and beyond were cancelled or postponed amid the spread of coronavirus.
Football has been called off in England, France, Italy and Spain, along with next week's fixtures in the UEFA Champions League and UEFA Europa League.
The Test series between Sri Lanka and England has been cancelled, while in golf The Players Championship was halted after one round and next month's Masters has been postponed.