Mauresmo earned the honour Monday when the new WTA rankings were released.
Mauresmo moved into the top spot from No. 2, unseating former No. 1 Justine Henin-Hardenne of Belgium. She took over the top spot despite losing in the U.S. Open quarter-finals last week in New York.
She is only the second player to reach No. 1 in the WTA rankings without winning a Grand Slam title.
France's Amelie Mauresmo is now the world's top-ranked women's tennis player. (CP Photo)
"Hopefully, now the Grand Slams will follow," Mauresmo said last week. "It's all about building things step by step. This gives me an incentive to work and work."
Mauresmo won the Rogers Cup title in Montreal last month.
Henin-Hardenne tumbled to fourth in the world after losing in the fourth round of the U.S. Open. She had been ranked No. 1 since Oct. 2003 – a span of 46 weeks.
Reigning French Open champion Anastasia Myskina of Russia moved up one place to a career-best No. 2, followed by No. 3 Lindsay Davenport of the U.S., Henin-Hardenne and No. 5 U.S. Elena Dementieva of Russia – the U.S. Open runner-up.
U.S. Open champion Svetlana Kuznetsova vaulted to a career-best sixth. Rounding out the top 10 are No. 7 Kim Clijsters of Belgium, No. 8 Jennifer Capriati of the U.S., No. 9 Maria Sharapova of Russia and No. 10 Serena Williams of the U.S.
Venus Williams remained in 12th spot.
with files from The Associated Press