After uninspiring wins over Austria and France and a narrow loss to Sweden last time out, the pressure was on the Finns to deliver a big win against the group's bottom side.
And they made the ideal start at the Avicii Arena less than three minutes in, when Eemil Erholtz controlled the puck behind the net before laying it back to Mikko Lehtonen, who guided home his first goal of the tournament.
The Finnish captain's wait for his second would be all of four-and-a-half minutes - he and Teuvo Teravainen evaded Slovenian pressure just inside the blue line before Lehtonen took aim and powered his shot into the top corner, giving Matija Pintaric no chance.
Two became three for Finland in the 12th minute, as Slovenia had no answer to Leni Hameenaho bursting into the attacking zone and laying the puck on a plate for Vili Saarijarvi, who made no mistake from in front of the net.
Hopes Finland had of recording a first shutout of the World Championship were crushed four minutes into the second period, when Slovenia pulled a goal back through Bine Masic.
Jan Drozg did well to get a shot on goal through traffic, and the rebound was picked up by Marcel Mahkovec, who teed up Masic to fire through a crowd and past Juuse Saros.
The HK Olimpija defender came within a whisker of a second less than a minute later - despite taking the puck around Saros, he failed to tuck it into the empty net from a tight angle.
But the Leijonat managed to relieve some of the growing tension seven minutes into the second. Terevainen came away with the puck at an attacking faceoff and played the puck across goal, where Seattle Kraken's Eeli Tolvanen was waiting to tap home.
Finland's best goalscoring performance of the championship was confirmed two minutes later when Hameenaho got in on the act - an attack which began behind their own goal ended in Waltteri Merala finding the New Jersey Devils man in space, and his shot went straight through Pintaric.
Late in the period, Slovenia could not force their way out of their own zone as Finland sustained a long period of pressure, which eventually culminated in Tolvanen being afforded too much space on the left side and he had no issue beating new goaltender Lukas Horak.
And there was still time before the 40-minute mark for Tolvanen to complete his hat-trick in fine individual style, picking up the puck in the Finnish zone before ghosting past the whole Slovenia defence and chipping the puck over Horak's shoulder to make it 7-1.
In the third period, further improvements to Finland's goal difference could not even be halted by being shorthanded - eight seconds after a high-sticking call against Juuso Parssinen, Nikolas Matinpalo was racing away down the right side and placing number eight past Horak.
Finland had to wait over 10 minutes for their ninth goal, but once again it was Terevainen the provider for Tolvanen to score his fourth of the match and sixth of the championship.
9-1 is how it finished as Slovenia's defence staved off Finnish attempts at double figures. The Lynx remain rooted at the bottom of the standings on zero points with a -17 goal difference after four matches.
The comprehensive win takes Antti Pennanen's team onto eight points and into third in the group. Next up for the Finns will be Latvia on Saturday.
Canada and Czech Republic win big
In the day's late games, both Canada and the Czech Republic scored big wins to continue their good respective form.
The Canadians, in Group A alongside Finland, went to the top of the table and maintained their perfect record with a 5-1 dismantling of Austria in Stockholm.
Over in Herning, the Czechs thrashed Hungary 6-1 to go top of Group B after four rounds.
Earlier in the day, in Group B, Switzerland beat Germany 5-1, and they are just one point behind the Czechs in the table.