The 36-year-old is making a second tour comeback having initially retired in 2007 following a combination of injuries and the desire to start a family.
This will be Clijsters' second comeback, as 10 years ago she already made a triumphant return to the court claiming three out of her four Grand Slam titles.
Fascinatingly, with Clijsters returning to action, that means that all the women who won three or more Grand Slams in the last 15 years are still playing... all except one.
"I have friends who would say, "I want to run the New York Marathon before I turn 50".
Clijsters said she has been considering a return to the tour for the past two years.
Despite her lengthy time out she still ranks third among active players in terms of tournament success behind the Williams sisters - Serena with 72 titles and Venus with 49.
Four-time grand slam victor Kim Clijsters has announced she is coming out of retirement and earmarked 2020 for a return to the court.
But the four-time grand slam victor has now announced a surprising return and is training with a view to playing again in 2020.
I'll be the hitting partner for your practice today.
The WTA said that as a former top-ranked player Clijsters can receive unlimited wildcards at its tournaments.
"It's a very satisfying feeling to have that kind of challenge again".
She then called time on her career again in 2012, and went on to have two more children Jack and Blake.
"I don't think like that, because I'm in the moment, and I know how much work I still have ahead".
"But then obviously I talked about it with my husband and with the team and then with Steve Simon from the WTA about being able to just hold off as much as possible to protect the children, obviously".
The former Belgian professional tennis player, 36, announced Thursday with a video on Twitter that she will be returning to the sport in 2020.
"Driven by her love for the sport, this wonderful champion continues to inspire women and men in all walks of life - and she only adds to the compelling wealth of talent in women's tennis. For me, I still love to play tennis", she said.