The former dancer fell ill with chest pains and a "roaring pulse" while filming weight loss show Excess Baggage in Sydney.
The 33-year-old, who came in at 16st 8lb at the beginning of the show, was treated by on-set paramedics, then taken to a medical centre in the city.
Photographs obtained by the Australian press show that he was made to wear an oxygen mask.
"During a challenge, the show's medic was concerned that Kevin's pulse rate was high so as a precautionary move, called an ambulance," a spokesperson for production company Fremantle Media told The Daily Telegraph.
The representative added that Federline is "undergoing further tests" in hospital.
Former rapper Federline was struck down with 'heat stress' while filming Excess Baggage in the Australian outback last December.
Federline claimed in 2010 that an addiction to fizzy drinks had led to his weight gain.
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