The American star took the lead above dancer Dita Von Teese and actress Sienna Miller in the list done by style bible Harpers & Queen.
The 35 year-old singer made her mark last year with her platinum blonde hair and ruby red lipstick.
She often wears styles by designers John Galliano or Vivienne Westwood.
The complete list of the top 100 best dressed women will be made public on April 11th. Here are the top ten:
1 Gwen Stefani
2 Dita Von Teese
3 Kate Moss
4 Sienna Miller
5 Natalia Vodianova
6 Cate Blanchett
7 Jacquetta Wheeler
8 Jasmine Guinness
9 Daphne Guinness
10 Zadie Smith