The 35-year-old, whose band have sold more than 3.5 million albums worldwide, is alleged to have conspired with a woman to rape a one-year-old girl, Cardiff magistrates heard.
He also stands accused of two incidents of conspiring to engage in sexual touching with two young children; possessing, making and distributing indecent images; and possessing “extreme” animal pornography.
The conspiracy charges related to a period between May 1 and Monday, while the indecent images related to a period between August 12 and Monday.
Defending barrister Tom Crowther said his client – dressed in a black hooded top and looking visibly tired – would be denying the charges and argued that his celebrity status could help to enforce bail conditions.
He also added that Lostprophets had cancelled a planned tour, Watkins had no previous convictions and his mother, who was sitting in the public gallery, was willing to put forward her house as a surety.
But presiding magistrate Alan Knight opted to remand Watkins – along with two women aged 20 and 24 – into custody.
The women, who face similar child sex allegations, cannot be named for legal reasons.
All three will appear before Cardiff Crown Court on December 31.
Earlier South Wales Police’s senior investigating officer, Detective Inspector Peter Doyle, appealed for information saying:
“Specially-trained staff are available to speak to anyone with concerns or information regarding this investigation and a dedicated telephone number has been set up.
“I want to encourage anyone who has any concerns or information which they think may be relevant to contact us.
“Safeguarding children involved in such cases is always a high priority and as such measures have already been taken.”