Ymer needed to come through three qualifying matches to reach the main draw - he saw off Australia's own Alex Bolt in straight sets, then won an all-Scandinavian meeting with Denmark's Elmer Moller in three sets, and finally got the better of Hong Kong's Coleman Wong in three sets.
It is the fourth time the 29-year-old has reached this stage of the Australian Open, but he is yet to go further, suffering first-round exits as a teenager in 2015, then in 2018 and 2021.
Ymer has reached the main draw at all four Grand Slams, with this appearance his ninth in total, but only once has he progressed to a second round, doing so at 2018's French Open.
The world number 175 will be taking on Kazakhstan's Alexander Shevchenko in the first round, which begins on 18th January.
Shevchenko, who was born in Russia and represented his homeland until 2024, is ranked 104th in the world, but Ymer was successful in straight sets in their only previous meeting, though that was on grass in Mallorca in June of last year. Neither player has reached the second round in Melbourne
The pair are in section four of the draw, with number seven seed Felix Auger-Aliassime of Canada the most likely opponent should they reach the third round, with 11th seed Daniil Medvedev a potential round four opponent.
In the men's doubles, Sweden's Andre Goransson and his new partner, Yuki Bhambri of India, are the 10th seeds for the competition, and are waiting to discover their first round opponents.
