The 25-year-old Henin, who retired Wednesday, asked to be removed from the rankings, the WTA Tour said Thursday. Sharapova will automatically become No. 1 when the next rankings are released Monday.
It will mark the fourth time the Russian has held the top ranking. She has been No. 1 for a total of 14 weeks in her career, the last in 2007.
"The ranking has never been a big deal for me," Sharapova said Wednesday after defeating Dominika Cibulkova in the second round of the Italian Open. "Whether I'm No. 1 or 5, my main goal is just to keep winning tennis matches and the ranking will take care of itself if I keep winning."
Henin, winner of seven Grand Slam titles, is the first woman to retire while holding the No. 1 ranking. This is the Belgian's 117th nonconsecutive week in the top spot, the sixth-longest reign at No. 1 since the computer rankings began in 1975.
After an injury-plagued 2007, Sharapova started 2008 by winning the Australian Open for her third Grand Slam title.