Defending champion Simona Halep defeated Kristina Mladenovic in the final, 7–5, 6–7(5–7), 6–2 to win the women's singles tennis title at the 2017 Madrid Open.

Mirjana Lučić-Baroni is a Croatian former professional tennis player. She enjoyed a meteoric rise on the WTA Tour in the late 1990s, during which she set several "youngest-ever" records. She captured the women's doubles title at the 1998 Australian Open when she was 15 years old, partnered with Martina Hingis. She also won the first ever professional tournament she entered, the 1997 Croatian Ladies Open, and defended it the following year at age 16, making her the youngest player in history to successfully defend a title. She then reached the semifinals of the 1999 Wimbledon Championships, beating world No. 4 Monica Seles, and eighth seed Nathalie Tauziat, the previous year's finalist, before she lost to Steffi Graf in three sets.