Brandon Seymour, 27, from Ebbw Vale, sexually abused two boys and a girl between 2019 and 2021, Cardiff Crown Court was told.
He was told by the mothers of his victims that he has devastated their lives.
Seymour, currently of Dyffryn Court, Abercarn, Caerphilly pleaded guilty to a catalogue of sexual offences.
The defendant admitted five counts of the sexual assault of a child under the age of 13, two of causing or inciting child a child under the age of 13 to engage in sexual activity and one of possession of indecent images of children.
The child abuse images were found on his mobile phone following his arrest.
Prosecutor Matthew Cobbe read out victim personal statements written by the children’s mothers.
One of them said: “Our lives have been devastated. I feel sick to my stomach.
“I could feel the anger boiling inside me.
“This was an exceptionally painful time in all our lives.”
Another mum told the court: “He’s a sick and twisted individual.
“He has ripped my soul apart. I wouldn’t wish this pain on anyone.”
The court was told the defendant was a man of previous good character with no convictions recorded against him.
The judge, Recorder Duncan Bould, told the defendant: “You have an unhealthy interest in prepubescent children.
“You groomed your victims.”
He told Seymour he was a “dangerous offender” and posed a high risk to children.
The defendant was jailed for 10 years in custody plus an extended licence period of five years.
He will have to serve two-thirds of the 10-year term before he is eligible for parole.
The defendant will have to register as a sex offender for life and pay a £228 victim surcharge upon his release from custody.