The 36-year-old Belgian did well in the return, but lost 2–6, 6–7 against Garbiñe Muguruza in the Dubai WTA tournament.
Clijsters, who has won four grand slam titles and been world-class throughout his career, made his first match in over seven years.
It was, to say the least, a tough first task for the Clijsters, as Muguruza played final in the Australian Open last month.
She left for the first time in 2007, but returned to the tour in 2009 and won the Australian Open in 2012 before retiring in 2012. As before, Clijsters has an unlimited number of wildcards for WTA tournaments and can therefore choose the number of competitions she wants to participate in.