Serena Williams won 23 Grand Slam singles titles, the most by any player in the Open Era. Her 23rd major came at the 2017 Australian Open, where she defeated her sister Venus Williams in the final. That victory moved Serena past Steffi Graf’s Open Era record of 22 singles majors.
Her titles span all four major tournaments: the Australian Open, French Open, Wimbledon, and US Open. She won the Australian Open seven times, the French Open three times, Wimbledon seven times, and the US Open six times. Her first major singles title was the 1999 US Open, when she defeated Martina Hingis.
A common mix-up is counting Serena’s doubles and mixed-doubles championships together with her singles total. Serena won 14 major women’s doubles titles with Venus and two mixed-doubles majors, but the answer to this question refers only to singles titles. Margaret Court has 24 major singles titles overall when pre-Open Era results are included, so Serena’s 23 is the Open Era record and the second-highest total in women’s tennis history.