It's a fifth World Championship gold for Finland, who had exited the previous three tournaments without a medal, while Switzerland have now been forced to settle for silver three years in a row, as their agonising wait for a first world title goes on.
The gold medal game was a rematch of both teams' final Group Stage fixture just five days earlier, which Switzerland edged 4-2 to top the group and set them on a path to wins over Sweden and Norway in the knockout rounds, while Finland saw off Czech Republic and Canada to reach the showpiece.
The two sides had scored 87 goals between them at the World Championship, but neither could find a way through in a tense opening period. The Swiss couldn't make use of the first powerplay after Aatu Raty was called for interference, nor could the Finns use their first after Calvin Thurkauf committed the same offence.
Seconds after the powerplay expired, Finland did have the puck in the hosts' net, but Anton Lundell's goal was disallowed after video review confirmed he played the puck above the height of the crossbar following a strike from Mikko Lehtonen.
Another chance for Antti Pennanen's side came and went after tripping by Dean Kukan inside the final five minutes of the first period, which ended with Urho Vaakanainen and Lundell both sent to the box for two minutes in the dying seconds.
The Finnish defence did superbly to not give away a single shot on goal in the first 1:55 of the second period despite the 5-on-3, which set the tone for a very tight period in which there had been just two shots on goal each in the first 15 minutes, even with Damien Riat's cross-checking giving Finland a powerplay halfway through.
Die Nati finished the period the stronger, forcing Justus Annunen into six more saves, but arguably their best chance fell to Pius Suter, who shot wide when space opened up for him on the right and the entire Swiss Life Arena was expecting the net to bulge. Instead, the 40-minute mark came with the match still goalless.
The start of the third period was just as light on chances, as it became increasingly likely that one goal would be enough for either side. Finland made it four powerplays without profit after Christian Marti was called for delay of game, but as the final 10 minutes approached, the Leijonat were very much on top.
Finnish pressure forced Thurkauf into conceding another penalty, this time for tripping, but the powerplay was cancelled out within seconds owing to high sticking by Helenius.
During the 4-on-4, Annunen did just enough to stop a Roman Josi effort trickling over the line, and then stood firm after Suter danced through the Finnish defence. After 22 shots on goal for Finland and 19 for the Swiss, the 2026 World Championship final reached 60 minutes with the score still 0-0.
After all that, the Final was almost settled within 30 seconds of overtime, as Jesse Puljujarvi beat Leonardo Genoni but struck the upright, then Switzerland's first big chance to win it saw Annunen save from Riat after almost four minutes.
Both goaltenders were in action again as the first 10 minutes of OT came and went, before at long last, the deadlock was broken with 10:42 played in the extra period, as Helenius picked up Lundell's pass at centre ice and carried it into the Swiss zone. There, he circled from left to right, taking his time before firing a clean shot past Genoni to win the title for Finland.
Finland celebrated their 1-0 triumph wildly, as much of the arena in Zurich fell silent as the hosts came to terms with falling short in the Final once again.
Earlier on Sunday, Norway recorded a memorable 3-2 overtime success over Canada in the third-place play-off to win bronze, their first medals in a major international competition.
Review the whole 2026 World Ice Hockey Championship on Flashscore.