The Romanian was free to return immediately and was given a wildcard for the Miami Open, where she lost to Spain’s Paula Badosa in round one.
Madrid will be the two-time Grand Slam champion’s second tournament back.
“Muchas gracias for this wildcard opportunity,” Halep posted on X.
“Madrid has always been a special tournament for me, with happy memories and I’m grateful to be able to make more.”
The Madrid Open starts on 22 April and concludes on 5 May.
Former French Open champion Halep is a two-time winner of the clay-court event, which is part of the WTA 1,000 series and one of the leading tournaments outside the four Grand Slams.
It is one of the key pillars of the European clay-court season, which culminates at the French Open in June.
Former world number one Caroline Wozniacki, who returned in August after having two children, has also received a wildcard, along with Japan’s injury-hit Kei Nishikori and Spanish teenager Martin Landaluce in the men’s singles.
Meanwhile, the ATP has announced the Madrid Open will launch the trial of a new men’s doubles format which the governing body says aims to “increase the exposure and marketing appeal”.
The major change will see 16 spots in the 32-team draw being given to pairs made up of singles players.
There will also be a streamlined five-day schedule for the event, while time between shots and changeovers will be reduced in an attempt to speed up matches.
