1997, 37 wins
No. 1 Victoria Azarenka got off to a flying start in 2012, winning her first 26 matches. There are only two women who have started seasons better than Azarenka, including three separate seasons in which Steffi Graf won 31 or more straight matches.
Hingis holds the record for the longest streak to open the season at 37 wins. She began 1997 ranked No. 6. But after winning six titles, including the Australian Open, she climbed to the top of the rankings by the time her 37-match winning streak ended in the French Open final.