Ian Watkins, 36, pleaded guilty last month to 13 charges, which included sexually touching a 1-year-old, encouraging a fan to abuse her child, and making child pornography.
Judge Roger John Royce told Watkins his actions had "plumbed new depths of depravity" and sentenced the singer on Wednesday at Cardiff Crown Court.
Watkins must serve at least two thirds of his 29-year sentence, then spend six more years on strict probation.
Lostprophets - which formed in 1997 and had a chart-topping album in 2006, "Liberation Transmission" - announced it was disbanding after Watkins' arrest.
