Paderborn clinched their second successive promotion to seal a Bundesliga return, despite losing 3-1 to Dynamo Dresden on the final day of the season.
Steffen Baumgart's men travelled to the DDV-Stadion with a one-point advantage over third-placed Union Berlin, while Cologne were already confirmed as 2. Bundesliga champions.
Philipp Klement gave Paderborn the lead after 10 minutes in Dresden, but Baris Atik hit a hat-trick to give Union the chance to steal promotion with victory over VfL Bochum.
Union were two goals down within four minutes of the second half and while they were given late hope thanks to goals from Grischa Promel and Joshua Mees, they failed to force a winner that would have secured them second place.
Urs Fischer's men still have an opportunity to make it to the top tier, however, as they will play Stuttgart, who finished 16th in the Bundesliga, in a play-off.
As for Paderborn, their latest promotion continues a dramatic five years in the club's history.
Following relegation to the second tier in 2015, they dropped down again the following year and only escaped relegation to the regional league in 2017 due to 1860 Munich failing to meet the deadline for a third-division licence.