Beijing will require all travellers to undergo a COVID-19 test within 72 hours of entering the Chinese capital until at least the end of March.
The rule will come into force on January 22.
Chinese Government newspaper Beijing Daily announced the rule, which will be in place throughout the Beijing 2022 Winter Olympic and Paralympic Games.
The measure is aimed at strengthening existing rules, which currently require travellers to be tested 48 hours prior to departure and having a green code on Beijing's health-tracking application.
The first case of the Omicron variant of COVID-19 was reported in Beijing yesterday.
The case comes with fewer than three weeks until the Opening Ceremony of the Winter Olympics.
Officials said the coronavirus variant, which is highly transmissible, had been detected in a patient and that all people who had come into contact with that person would be tested.
The case was announced little more than two weeks before Chinese New Year celebrations, which should begin on February 1.
Millions of people traditionally travel across the country for China's biggest holiday.
Mass testing has been taking place in Tianjin after 97 cases of the Omicron variant were identified in the city, which is situated fewer than 150 kilometres from Beijing.
Anyang became the third Chinese city to be placed into lockdown last week due to the emergence of Omicron infections after Xi’an and Yuzhou were impacted in previous weeks.
The Beijing 2022 Winter Olympics are scheduled to take place from February 4 to 20, shortly after Chinese New Year.
All Olympic participants will enter a "closed-loop management system" when they get to China.
Participants will only be able to visit Olympic venues and use designated transport, ensuring they will have no contact with the Chinese public.
Once within the loop, people will undergo daily testing for COVID-19.
Unvaccinated participants must complete a three-week quarantine period before they are allowed to travel to approved locations.
The increase in cases of the Omicron variant has raised further doubts over the attendance of domestic spectators at the Games.
Overseas spectators have already been prevented from attending the Games.