Defending champion Margaret Court defeated Rosie Casals in the final, 6–2, 2–6, 6–1 to win the women's singles tennis title at the 1970 US Open.

With the win, Court completed the Grand Slam, the first woman in the Open Era to do so in singles.

It was her fourth US Open singles title and record 20th major singles title, surpassing Helen Wills Moody's all-time tally.