Australian Open: Cibulkova enters semis
The 20th seed, in her best performance at Melbourne Park, marched past the Romanian 6-3, 6-0 and will play either defending champion Victoria Azarenka or fifth seed Agnieszka Radwanska in the last four.
The short but energetic Cibulkova drew on her experience to down the aggressive baseliner, who went into the clash as favourite after a breakthrough season last year when she won six titles.
Dominika Cibulkova celebrates a point. Pic/ AFP
The Slovak, who beat Maria Shaparova to get her chance against Halep, is now in her second career Grand Slam semi in 26 attempts, with the last one coming at the French Open in 2009.
But she has also previously made the quarters at all the other Slams, and she said this gave her a vital edge against Halep, who was in the last four of a major for the first time.
"One hundred percent, I have experience on these important matches and I knew how to react on court and I did everything perfect today," she said.
"The match against Maria took everything out of me but my fitness is good so I came through."
Cibulkova, who has won three career singles titles, including at Stanford last year where she beat Radwanska in the final, raced through her opening serve and immediately broke a nervous Halep when the Romanian sent a forehand long.
Halep, voted the most improved WTA player last year, was struggling to get into the game and quickly went 3-0 down.
A powerful and pinpoint cross-court backhand after a long rally gave her confidence in the next game as she served to love, and she appeared to be getting into her groove.
She created two break point chances in the next game, but failed to convert either.
But she was applying pressure and Cibulkova cracked on her next service game with three double faults to bring Halep back to 4-3. But that was as good as it got for the Romanian.
She immediately threw away her advantage by getting broken in the next game, and the Slovak made no more mistakes to take the set in 34 minutes.
Cibulkova was firing and a forehand into an empty court gave her a break to go 1-0 up in the second set, and there was no looking back as a dispirited Halep's game fell apart and the Slovak raced through the set in 26 minutes.
Despite the defeat, Halep is forecast to move into the world's top 10 when the new rankings are released on Monday, at the expense of Dane Caroline Wozniacki.