In 1895 he returned to Belgium and shortly after his arrival he was one of the founding members of the Belgian Football Association on 1 September 1895.

[citation needed] He then joined Sporting Club de Bruxelles, which participated in the very first edition of the Belgian Championship in 1895–96, and König helped his side to a 3rd place finish just behind Antwerp FC and champions F.C.

As a result, he was a very fast and dangerous player in football, being the top scorer in the Belgian Championship two successive times in 1898 and 1899.

[5] König was a member of the Belgian squad who won a bronze medal in Paris, acting as coach of a team made up almost entirely of students of the University of Brussels.

[6] König refereed his first and last international match on 30 April 1905, a Low Countries derby between Belgium and the Netherlands in the 1905 Coupe Vanden Abeele, ending in a 4–1 win to the Dutch after extra-time, but more important than the result was its historic relevance since it was the Dutch's very first official game.