By the 1979–80 season, Willmer had established himself in Köln's first squad, and helped them to another DFB-Pokal final, this time a 2–1 defeat against Fortuna Düsseldorf in which he appeared as a substitute for Pierre Littbarski.
The following year Bayern won another title, leap-frogging Werder Bremen on the last day of the season with a 6–0 win over Borussia Mönchengladbach.
Willmer sat this match out, but featured in a second consecutive cup final - replacing Michael Rummenigge late in the game as Bayern did complete the double this time, beating VfB Stuttgart 5–1.
The following season, Willmer was less involved in the first team, making nine appearances as Bayern won a third consecutive German title.
Bayern also reached the European Cup Final, and Willmer was an unused substitute for the 2–1 defeat against FC Porto.