Jankovic's 4,555 points give her a commanding lead over Dinara Safina (3,782) and Serena Williams (3,716). She will retain the top spot regardless of the outcome of the season-ending Sony Ericsson Championships in Doha, the WTA Tour announced Saturday.
"It has been a truly amazing year for me,'' Jankovic said. "I worked really hard this year, and to finish No. 1 is where I want to be and where I hope to stay.''
The 23-year-old, who hasn't won a major, lost to Williams at the U.S. Open final in September. She won four titles and is 63-17 so far this year.
Jankovic secured the year-end ranking by winning 12 straight matches en route to three consecutive titles: the China Open in Beijing, the Porsche Tennis Grand Prix in Stuttgart, Germany, and the Kremlin Cup in Moscow.
She first claimed the No. 1 ranking on Aug. 11, holding it for one week. She regained the top spot on Oct. 6 following her win in Stuttgart.
She also advanced to the semifinals of two other Grand Slams, losing to eventual champion Maria Sharapova at the Australian Open and eventual champion Ana Ivanovic at the French Open.
The other players to hold the top ranking were the retired Justine Henin (20 weeks), Ivanovic (12), Sharapova (three) and Williams (four).
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