Halep, who was beaten in the final at Roland Garros last year, is now two wins away from her maiden Grand Slam title and takes on Spain’s Garbine Muguruza next.
Muguruza thumped twice former champion Maria Sharapova to reach her fourth Grand Slam semi-final. The Spaniard was flawless in her 6-2 6-1 win and will be the firm favorite to lift the title for the second time in Paris.
Holder Rafa Nadal’s run of winning 37 consecutive completed sets at Roland Garros was snapped by Diego Schwartzman as the Argentine raced to an early lead in their quarter-final.
Nadal, chasing a record-extending 11th French Open title, regrouped and led 5-3 in the second set when rain ensured that the pair would resume their match on Thursday.
In the other last-eight clash, Marin Cilic and Juan Martin del Potro were locked in a tight tiebreak battle for the first set before rain stopped play.