Nightclubs have reopened, late-night alcohol sales have resumed, and the contact-tracing app is no longer needed to enter venues.
While cases are still relatively high, the authorities say the virus no longer qualifies as a "critical threat".
That is due to the country's high vaccination rate, experts say.
"We have an extremely high coverage of adults vaccinated with three doses," epidemiologist Lone Simonsen of the University of Roskilde told the AFP news agency.
"With Omicron not being a severe disease for the vaccinated, we believe it is reasonable to lift restrictions," she said.
From Tuesday, masks are no longer required in shops, restaurants, and on public transport. Limits on the number of people allowed at indoor gatherings and social distancing measures also come to an end.
The national contact-tracing app is no longer required - although individual event organisers can still choose to make it a condition of entry.
Some rare restrictions will remain in place - for example, for unvaccinated travellers attempting to cross the border from outside Denmark's free travel zone, or the use of face masks in hospitals and care homes.
Danish Prime Minister Mette Frederiksen welcomed the move, writing "good morning to a completely open Denmark" on Facebook and thanking the population for getting vaccinated.
"I'm so happy that this is all going to be over tomorrow," 17-year-old student Thea Skovgaard told AFP on Monday. "It's good for life in the city, for nightlife, just to be able to be out longer."
The easing of restrictions in Denmark follows similar decisions in England and other UK nations in January. Other EU member countries - such as Ireland, France, and the Netherlands - have also begun to remove their restrictions.
