Renewed Covid prevention measures will target bars and restaurants in Päijät-Häme, Kymenlaakso and Southwest Finland, which health experts said were in an "acceleration phase" of the epidemic.
Bars and restaurants in these regions will close by 1am and see alcohol service end by midnight. These rules currently apply to Uusimaa where they will also remain in place.
Family Affairs and Social Services Minister Krista Kiuru (SDP) told Yle on Friday that the government was asking the Ministry of Social Affairs and Health to implement the new restrictions on bars and restaurants as of next Thursday, 22 July.
Cases in Finland have tripled since mid-June, with the highly transmissible Delta variant playing an increasing role in new infections. Health officials said recent cases have mostly been traced to bars and nightlife among people between the ages of 20 and 29.
Several infections have, for example, been linked to the Hanko Regatta sailing event last weekend.
"Get your shots"
Kiuru also urged people in Finland to get their jabs.
The number of positive samples has tripled within a month, and Finland is now recording more than 1,600 infections each week. Nearly 50 people are currently being treated in hospital for Covid-related complications.
"Soon we will be in a very similar situation to last October," the minister said. "We are heading in a worrying direction, we are in a race of sorts. Vaccine coverage rates are rising, but the Delta variant is also spreading rapidly."
Kiuru said fans returning from the European Football Championships in St. Petersburg were not solely to blame for the new spike in cases.
"Infections have also come with foreign workers and holidaymakers. Our task is to keep Finland open, and now it is everyone's personal responsibility to ensure that they follow health guidance."
Around 63 percent of the Finnish population has received their first dose of the coronavirus vaccine while more than one in four is fully vaccinated.
"The progress of vaccine coverage is the alpha and omega. Our job is to ensure everyone makes it to their vaccination appointment," Kiuru said, adding that she was concerned about people not showing up for their boosters.
"For crying out loud, please get the vaccine. We are still in a vulnerable position in the face of the Delta variant. You will not be fully protected until after the second dose of the vaccine."
If people stick to their appointments, Kiuru estimated that by the end of October, vaccine coverage could be extensive enough to protect Finland against fast-spreading mutations such as the Delta variant.
On Thursday the City of Helsinki said it was cutting the interval between first and second Covid vaccine doses from 12 to eight weeks.