The 22-year-old Russian became the 19th player to head the WTA list since the introduction of computer rankings in 1975.
The WTA website said: "Safina has had a phenomenal last 12 months, collecting four Tour titles at Berlin, Los Angeles, Montreal and Tokyo, all last year; and reaching another five finals."
Safina, who will keep her ranking for at least two weeks, said in an interview with French L'Equipe newspaper that her goal was to remain world No. 1 for longer than her older brother Marat Safin, who topped the men's ATP ranking for around nine weeks from November 20, 2000.
"I will celebrate this feat with Marat in mid-May in Madrid. This is amazing that I have become just like my brother, who I always admired. Earlier I used to be just his younger sister, but now I am Dinara," she said.
The top 10 of new WTA ranking includes four other Russians.
1. Dinara Safina (Russia)
2. Serena Williams (USA)
3. Elena Dementieva (Russia)
4. Jelena Jankovic (Serbia)
5. Venus Williams (USA)
6. Vera Zvonareva (Russia)
7. Ana Ivanovic (Serbia)
8. Victoria Azarenka (Belarus)
9. Svetlana Kuznetsova (Russia)
10. Nadia Petrova (Russia)
