Venhuizen started skating at the age of five. In the 1999–2000 season, she debuted on the ISU Junior Grand Prix (JGP) series and then won her first senior national title, earning assignments to her first ISU Championships. In February 2000, she reached the free skate and finished 21st overall at the European Championships in Vienna after placing tenth in her qualifying group, 23rd in the short, and 21st in the free. In March, she competed at the 2000 World Junior Championships in Oberstdorf; she advanced out of her qualifying group but was eliminated after the short program.