With the coronavirus infection rate in the country at just under 550 cases per 100,000 people and rising, the government opted for an open-ended ban on crowds beginning with the festive season.
Earlier on Tuesday (AEDT), Cardiff City's scheduled Boxing Day game against Coventry City in the Championship was postponed, the second consecutive Bluebirds game called off due to coronavirus cases among the squad and staff.
Several other fixtures across multiple sports also have been called off amid COVID-19 concerns.
Amid that environment, Wales economy minister Vaughan Gething announced the new restrictions early on Tuesday (AEDT).
"Sporting events over the Christmas period are one of the big highlights of the year," Gething said in a release. "Unfortunately, the new Omicron variant is a significant development in the pandemic and could cause a large number of infections.
"We need to do everything we can to protect people’s health and control the spread of this awful virus.
"Throughout the pandemic we have followed scientific and public health advice to keep people safe. The advice is clear – we need to act now in response to the threat of Omicron. We are giving people as much notice of these decisions as we can.
"Crowds will come back as soon as possible. We want everyone to be here to enjoy their favourite sports."
In addition to league competition, the new restrictions likely will affect FA Cup play. Swansea City is set to host Southampton in a third-round tie on 8 Januar, with Cardiff City to host Preston North End the day after.