The move came after the 24-year-old sprinter refused to fly home from Tokyo on Sunday, claiming that her team was trying to force her on board the plane against her wishes.
She arrived at the building in an unmarked silver van at about 5pm local time (08:00 GMT), Reuters news agency reported. She stepped out with her official team luggage and was greeted by two officials before entering the premises.
Deputy Foreign Minister Marcin Przydacz said Tsimanouskaya was in “direct contact” with Polish diplomats in Tokyo.
“She has received a humanitarian visa,” he tweeted. “Poland will do whatever is necessary to help her to continue her sporting career.”
Przydacz told Reuters Tsimanouskaya was “safe and in good condition” after arriving at the Polish embassy.
Foreign ministry officials were quoted by Polish media as saying they expected her to travel to Poland this week.
The Belarusian Sports Solidarity Foundation told The Associated Press news agency that the group had bought her a plane ticket to Warsaw for Wednesday.
Meanwhile, a Ukrainian interior ministry source told Reuters that Tsimanouskaya’s husband, Arseni Zhdanevich, had entered Ukraine.
It was not immediately clear whether he was making his way to Poland to be reunited with his spouse.
‘I was put under pressure’
The current standoff apparently began after Tsimanouskaya criticised how officials were managing the Belarusian Olympic team.
She was then apparently hustled to Tokyo airport but refused to board a flight destined for Minsk via Istanbul and instead approached the police for help.
In a filmed message distributed on social media, she also asked the International Olympic Committee (IOC) for assistance.
“I was put under pressure, and they are trying to forcibly take me out of the country without my consent,” she said in the message.
But the Belarusian Olympic Committee said in a statement that coaches had decided to withdraw Tsimanouskaya from the games on doctors’ advice about her “emotional, psychological state”.
Belarus athletics head coach Yuri Moisevich told state television he “could see there was something wrong with her … She either secluded herself or didn’t want to talk”.
On Monday, IOC spokesman Mark Adams said officials would continue conversations with Tsimanouskaya and had asked for a full report from the Belarusian Olympic Committee.
The Japanese government said she had been kept safe while organisers of the Tokyo 2020 Summer Games and the IOC checked her intentions.
“Japan is coordinating with relevant parties and continues to take appropriate action,” said chief cabinet secretary, Katsunobu Kato.
The incident has focused renewed attention on the political discord in Belarus, a former Soviet state that is run by longtime President Alexander Lukashenko.
Authorities there have relentlessly cracked down on dissent following a wave of protests triggered by an August 2020 election that was denounced by the country’s political opposition as rigged.
Lukashenko, in office since 1994, denies the allegations of vote-rigging.