The 31-year-old American becomes the oldest ever woman to claim top spot following her run to the Doha final, moving 265 points clear of Azarenka with Russia's Maria Sharapova remaining third.
"I never thought I would be here again," she said tearfully to a cheering crowd after her victory over former Wimbledon champion Petra Kvitova on Friday was enough to guarantee her climb back to the top.
"Oh, my gosh, I've been through so much. I never thought I would be here."
After winning Wimbledon and the US Open last year, Williams' total of Grand Slam titles has risen to 15, only three fewer than retired greats Martina Navratilova and Evert, who together are second on the all-time list behind Steffi Graf with 22.
1. Serena Williams (USA) 10590 pts (+1)
2. Victoria Azarenka (BLR) 10325 (-1)
3. Maria Sharapova (RUS) 9715
4. Agnieszka Radwanska (POL) 7750
5. Na Li (CHN) 6130
6. Angelique Kerber (GER) 5400
7. Sara Errani (ITA) 4820
8. Petra Kvitova (CZE) 4510
9. Samantha Stosur (AUS) 3835
10. Caroline Wozniacki (DEN) 3570
11. Marion Bartoli (FRA) 3215
12. Nadia Petrova (RUS) 3000
13. Ana Ivanovic (SRB) 2896
14. Maria Kirilenko (RUS) 2701
15. Dominika Cibulkova (SVK) 2695
16. Sloane Stephens (USA) 2535 (+1)
17. Roberta Vinci (ITA) 2535 (-1)
18. Lucie Safarova (CZE) 2065
19. Ekaterina Makarova (RUS) 1950 (+1)
20. Julia Görges (GER) 1915 (-1)
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