Anastasia Pavlyuchenkova was the defending champion and successfully defended her title, defeating Madison Brengle in the final, 7–6(8–6), 7–6(7–3).
Anastasia Pavlyuchenkova was the two-time defending champion, having won the junior Australian Open titles in 2006 and 2007, but lost in the quarterfinals to Simona Halep.
Serena Williams was the defending champion, but withdrew due to injury.
Shelby Rogers was the defending champion, but decided not to participate.
Melanie Oudin was the defending champion, having won the event in 2013, but lost in the second round to Jennifer Brady.
Garbiñe Muguruza was the defending champion heading into the tournament but chose to compete at the Sydney tennis event instead of Hobart. In the final, it was unseeded Brit Heather Watson who defeated the American qualifier in Madison Brengle, 6–3, 6–4 to record her second WTA title.
Kurumi Nara was the defending champion, but chose to compete in Dubai instead.
Anna Schmiedlová was the defending champion, but chose not to participate.
Samantha Stosur was the defending champion, but chose not to participate.
Angelique Kerber was the defending champion and successfully defended her title, defeating Laura Siegemund in the final, 6–4, 6–0.
Belinda Bencic was the defending champion, but lost in the second round to Elena Vesnina.
Yanina Wickmayer was the defending champion, but lost in the first round to Viktorija Golubic.
Taylor Townsend was the defending champion, but chose not to participate.
Caroline Garcia was the defending champion, but lost in the semifinals to Daria Gavrilova.
Caroline Wozniacki was the defending champion and successfully defended her title, defeating Anastasia Pavlyuchenkova in the final, 6–0, 7–5.
Tatjana Maria was the defending champion, but chose to compete at the 2018 St. Petersburg Ladies' Trophy instead.
Madison Brengle was the defending champion but lost in the second round to Mari Osaka.
Sofia Kenin was the defending champion, but chose not to participate.
Madison Brengle was the defending champion but lost to Caty McNally in the quarterfinals.
Mariana Duque Mariño was the defending champion, but she had retired from professional tennis earlier in the year.
