The 'We Found Love' singer paid £15,000 for her stylist Ursula Stephen to be flown to London from Los Angeles to resolve the problem, according to The Sun.
The 24-year-old, who is filming her appearance on Saturday's Jonathan Ross Show tonight, apparently did not trust a local hairdresser.
Her hair had become "tangled" and "matted" in a hotel sauna after going for a swim, a source claims.
"When she got out, her hair was tangled and matted. She slapped a load of conditioner on but it didn't get through the mass," the insider continued.
"She didn't want to take the chance on an unknown. Because they were on such a tight schedule, they had to get her on the first flight.
"Rihanna didn't care about paying a fortune. [She] shoved a hat on to go to the studios. She was fine when she knew Ursula was on her way."
Watch Rihanna performing 'We Found Love' at last week's Brit Awards below: