With top three seeds Serena Williams, Li Na and Agnieszka Radwanska having already been eliminated, fifth seed Kvitova was dumped out in the third round to become the latest star name to exit Roland Garros prematurely.
The Czech, nursing a heavily strapped thigh, was involved in an epic back-and-forth contest with 2009 champion Svetlana Kuznetsova, the Russian needing over three hours to earn a 6-7 (3-7) 6-1 9-7 triumph.
Kvitova was in noticeable discomfort against the 27th seed, but sportingly admitted after the match that Kutznetsova was a worthy winner.
Lucie Safarova is the next challenger awaiting Kuznetsova, the Czech producing a fine performance to easily see off the threat of 11th seed Ana Ivanovic 6-3 6-3.
It marks the fifth time in a row the 23rd seed has beaten Ivanovic, the last four coming in straight sets.
Halep is now the highest ranked seed left in the competition, and the Romanian progressed to round four for the first time in her career with an utterly dominant 6-3 6-0 win over Maria-Teresa Torro-Flor.
The 22-year-old has won seven WTA Tour titles in the past year in what has been a fine surge up the rankings, though she was helped somewhat by 24 unforced errors from Torro-Flor.
She is sure to face a tougher test in round four against Sloane Stephens, the American having made the second week of six straight majors after seeing off Ekaterina Makarova 6-3 6-4.
Elsewhere, Jankovic is emerging as one of the favourites in Paris, and she showed why with a superb 6-1 6-2 rout of Sorana Cirstea.
Cirstea had a 3-2 head-to-head record before the encounter, and had beaten Jankovic in round four in 2009, but she was no match for the sixth seed on this occasion.
Jankovic's reward is a fourth-round clash with Sara Errani, the Italian 10th seed dropping just one game in a crushing 6-0 6-1 success over Julia Glushko.
Rounding off the action, Kiki Bertens defeated Silvia Soler-Espinosa 6-2 6-1, and booked a fourth-round date with Andrea Petkovic who defeated Kristina Mladenovic 6-4 4-6 6-4.