Two men, aged 41 and 71, died at a hospital in the southwestern city of Wrocław, the country’s health ministry said in a tweet.
Meanwhile, a 71-year-old man died in the southwestern town of Bolesławiec.
The health ministry said that all three men had been suffering from underlying medical conditions.
The number of confirmed coronavirus cases in Poland rose by 56 on Wednesday, bringing the total to 957.
On Tuesday, 152 new infections were confirmed by the health ministry, the highest number in a single day.
The first infection was confirmed by Polish authorities on March 4, while the country's first coronavirus fatality was announced on March 12.
Poland has declared a “state of epidemic" and temporarily closed its borders to non-residents in a move to curb the spread of the illness.
International scheduled flights and passenger rail connections have been suspended. The government is chartering special flights to help Poles abroad return home.
In another move to contain the spread of the COVID-19 epidemic, the government has limited the operations of shopping malls and closed all pubs, clubs and entertainment venues.
Public gatherings of more than two people have been banned.
The Polish health ministry said on Tuesday that 1,479 people with suspected coronavirus infection were in hospitals nationwide, with a further 62,511 quarantined, 104,529 ordered to self-isolate after arriving from abroad, and 53,426 under epidemiological supervision.
Health and government officials have urged Poles to stay home and practice social distancing.