The deal between Nike and the former world No. 1, who competed in the Australian Open without a sponsor, is to be effective immediately, with Halep competing on Wednesday at the Qatar Open, reports Efe.
"I Just Did It," Halep tweeted, in comic reference to Nike's slogan 'Just Do It.'
Halep is to receive nearly $2 million a year, some $800,000 more than her deal with German athletic brand Adidas, from which she split after four years of collaboration, according to Romanian media.
The 26-year-old now joins the list of top tennis players sponsored by Nike, including Serena Williams of the US, Maria Sharapova of Russia, Rafael Nadal of Spain and Roger Federer of Switzerland.
This sponsorship agreement comes several days after Halep's recovery from severe dehydration, which sent her to the hospital following her loss in the punishingly hot Australian Open final against Caroline Wozniacki of Denmark on January 27.