Since 1981 she is an acting referee. From 1991 to 2004 she was registered in the list of the German Football Association, from 1998 to 2003 in the list of the Fifa. In the year 2000 she umpired the women's DFB-Cup's finale in Berlin. Furthermore she acted there as linesman triply, 1995, 1998, 2001 and 2007. She was internationally acting in several international matches as well as in the UEFA Women's Championship 2001 in Germany. Monika Fornaçon was also admitted as referee for men's Oberliga from 1998 to 2003.
In 2007 Monika Fornaçon quit being referee. From now on she operates i.a. as an observer for other referees and is on the committee of referees in the Niedersächsischer Fußballverband (=Association of Football in Lower-Saxony).