The 23-year-old is said to have undergone the age-defying procedure four times since competing in the ITV contest and, according to The Mirror, wore a hairpiece on the show last Sunday (November 20) after a botched jab gave him the appearance of having a receding hairline.
"Marcus admitted having Botox but it is not an official treatment set up by bosses," an X Factor source confirmed. "He is really embarrassed his secret is coming out. He denies having a hairpiece."
Collins has come under fire in the wake of the revelations, with medical experts arguing that the singer is setting a bad example to young fans with his affinity for vanity procedures.
"The people looking after him should be saying no," said Lesley Reynolds Khan of the Harley Street Skin Clinic. "He has a whole lifetime to worry about lines."
Collins was allegedly stunned this week after receiving racist and homophobic abuse in an early-morning phone call.
> 'X Factor' Marcus Collins: 'I want to break boundaries'