Kaia Kanepi started playing tennis at age 8 with parents and sisters. One of her sponsors is a leading provider of high-quality mini-cruise and passenger services in Baltic Sea region. In 2008 she reached her first Grand Slam quarter-final at Roland Garros and became the godmother of a vessel named Superstar and was flown to Italy to bless it. She reached the last 8 at Roland Garros (also in 2012), Wimbledon (2010, 2013) and US Open (2010, 2017) at Grand Slam level.
At 2010 Wimbledon, she became only the sixth qualifier to reach the last 8 at the Championships. That season, At the 2010 Internazionali Femminili di Palermo, Kanepi won her first WTA singles title defeating top seed Flavia Pennetta for the title.
In 2012 she managed to win more than a title in a single season for the only time in her career. She opened the campaign in Brisbane and clinched the second title of her career after beating Alexandra Panova, number seven seed Anastasia Pavlyuchenkova, number two seed Andrea Petkovic, number three seed Francesca Schiavone and Daniela Hantuchová. Kanepi then went on to win her third WTA title at the 2012 Estoril Open, defeating Carla Suárez Navarro in the final. An Achilles bilateral injury caused Kanepi to withdraw from Birmingham, Eastbourne, Wimbledon and the Summer Olympics in London. Kanepi returned from injury at the 2012 KDB Korea Open but lost her third final of the year to Caroline Wozniacki.
In 2013, she battled injuries missing first three months due to right Achilles injury and sidelined after Wimbledon until US Open due to a low back injury. She reached the quarterfinals at the Mutua Madrid Open and claimed her fourth title at the Brussels Open (d. Peng Shuai).
Kanepi advanced to quarter-final stage four times in 2014 (Brisbane, Acapulco, Bastad and Seoul) and posted a round-16 finish at US Open (l. S.Williams). She opened the 2015 campaign with a quarter-final appearance in Brisbane (l. Ivanovic) and finished the season on a high note by winning ITF title at Bangkok (d. Schnyder). But she fell at first hurdle at all Grand Slams with exception of a second-round finish at US Open (l. Svitolina).
From 2016, a combination of being diagnosed with the Epstein-Barr virus, otherwise known as a precursor to mononucleosis, and developing plantar fasciitis in both feet, nearly led to the end of her career. She endured a career-low year-end ranking of No.302 in 2016, having played a lone main draw match in Rabat (as qualifier, l. Kozlova). She played limited events on ITF Circuit, achieving the quarterfinals in Padova (l. Soylu) and the round 16 in Brescia (l. Zanevska).
Kanepi battled through yet another injury-plagued season, finishing 2017 at No.100. That season highlight was advancing to quarter-finals stage of 2017 US Open (l. eventual R-Up Keys). She also won three ITF titles.
Kanepi holds many firsts for her country. She is the first Estonian to reach a WTA final (2006 Hasselt), first to reach a Grand Slam quarter-final, to crack Top 20 (February 2009), to win a WTA title (2010 Palermo) and to beat a reigning No.1 (Wozniacki at 2011 Tokyo [PPO]).