Denmark hosted Slovenia in a winner-takes-all encounter at the top of Group H, with the two sides level on points and the winners of the match guaranteed a top-two finish.
Kasper Hjulmand's side took the lead through Joachim Maehle after 26 minutes to temporarily leapfrog their opponents at the summit, although their lead in both the group and on the night was short-lived.
Erik Janza equalised with a fine free kick from just outside the box four minutes later, and the two sides went into the break all square - a result which would have left both teams needing to wait until the final matchday.
However, Thomas Delaney restored Denmark's lead after Slovenia failed to clear their lines from a corner, and that goal nine minutes into the second half proved to be the winner as the Euro 2020 semi-finalists ensured that they would also be present in Germany.
Earlier in the day, Albania stamped their ticket with a 1-1 draw in Moldova, having gone into their penultimate Group E match knowing that they simply needed to avoid defeat in order to progress.
Sokol Cikalleshi opened the scoring for the visitors in Chisinau after 25 minutes, converting from the spot after Ioan-Calin Revenco had fouled Taulant Seferi.
That left Moldova needing two goals to prevent Albania from reaching Euro 2024 with a game to spare, but they left it too late with Vladyslav Baboglo's close-range equaliser only arriving in the 87th minute.
The result sees Albania qualify for just a second-ever major tournament, after Euro 2016, while they and Denmark become the 12th and 13th teams to confirm their place in Germany next summer.
Czech Republic also had the chance to qualify from Group E this evening, but they were held to a draw by Poland, who can no longer qualify automatically themselves having now played all of their matches.
Elsewhere in qualifying on Friday, an underwhelming England edged past Malta, Italy hit five past North Macedonia to boost their chances of qualification going into their winner-takes-all clash with Ukraine, Finland hammered Northern Ireland 4-0 and Kazakhstan saw off San Marino.