Steinhaus became a referee for the club SV Bad Lauterberg and began in the Frauen-Bundesliga after receiving DFB certification in 1999, having taken professional courses since the age of 15. She moved to the Regionalliga in 2001 and was the main referee for the 2003 DFB-Pokal der Frauen Final between 1. FFC Frankfurt and FCR 2001 Duisburg in 2003. Steinhaus began refereeing in the men's 2. Bundesliga in 2007, making her the first female referee in German men's professional football. She was also selected for the 2008 FIFA U-20 Women's World Cup, UEFA Women's Euro 2009, and 2010 FIFA U-20 Women's World Cup. In 2016, she changed her affiliation to MTV Engelbostel-Schulenburg.