The X Factor judge is thought to have contracted the tropical disease while on holiday in Tanzania with dancer pal Derek Hough, 25, last month.
On Saturday, Cheryl, 27, reportedly fainted during a photo shoot at a north London studio.
She was initially diagnosed with severe exhaustion, but after her condition deteriorated on Sunday, she was taken to hospital for further tests.
Cheryl is thought to have taken antimalarial drugs during her trip but the parasite can be resistant to medication.
Symptoms of malaria include fever and chills, the shakes, headache, muscle aches and fatigue.
Chezza's spokesman confirmed she has malaria, reports The Sun. She will be monitored by doctors for the next few days.
Yesterday, her team revealed she has pulled out of recording The X Factor auditions.
'Following doctor's advice Cheryl Cole will be cancelling all work commitments for the next week,' reads a statement from her rep on Twitter. 'No further comment.'
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