Cologne have returned to the Bundesliga one year after relegation, securing top spot in the second division with a 4-0 home win over Kaiserslautern on Sunday.
Cologne won thanks to goals from Eric Martel, Luca Waldschmidt, Florian Kainz and Mark Uth.
Even a second-half penalty miss by Waldschmidt could not derail Cologne's charge to the top flight.
Cologne will join Hamburg, who were promoted after seven seasons in the second league last weekend. Hamburg's 3-2 loss at Fuerth on Sunday meant they fell from first to second, the last automatic promotion spot, allowing Cologne to win the division.
Elversberg won 2-1 at Schalke to finish third and will take on Heidenheim, the third-last first division club, in a two-legged relegation playoff to decide who will play in the Bundesliga next season.
Holstein Kiel and Bochum were already relegated to the second division last weekend.
Cologne's promotion ends a tumultuous fortnight for the club, who sacked coach Gerhard Struber and sporting director Christian Keller in early May with the promotion in jeopardy.
Promotion specialist Friedhelm Funkel was named coach, serving his third stint at the club. This is the seventh time the 71-year-old Funkel has coached a club to promotion.
Relegated at the end of the 2023-24 season, Cologne's woes were compounded when local rivals Bayer Leverkusen broke through for their first Bundesliga title.
A founding member of the Bundesliga in 1963-64, Cologne were first relegated in 1997-98 and since then have bounced between the top two divisions, with this their seventh promotion in that time.
Cologne, created out of a merger in 1948, have won three German titles, with the last coming in 1977-78.