He also pleaded guilty at the beginning of his trial to indecency with a girl aged 12-16.
Bell appeared in the High Court at Whanganui yesterday, where Justice David Collins sentenced him to eight years in prison, with a minimum non-parole period of five years.
One victim tearfully read out her victim impact statement to the court, and 11 more statements were read out by officer in charge Senior Constable Tanya Ross.
The details of the victim impact statements, as well as submissions from Crown prosecutor Harry Mallalieu and defence lawyer Fergus Steedman, were suppressed by Justice Collins, as Bell faces another trial on similar charges.
Bell's offending started in 1999, when he indecently touched a four-year-old girl.
He was previously convicted in Napier, in January 2014, of three indecent assault charges, and sentenced to two years imprisonment.
"The trauma experienced by the victims as a result of this offending has been significant, and I know that reliving the trauma by giving evidence has been extremely difficult," said Ms Ross in a press statement. "I applaud them for their courage in coming forward, and I hope that today's sentence will contribute to their healing."
As Bell was taken from the courtroom, the father of one victim called out, telling him to "die in prison, you prick".
The man said he would kill Bell himself. People could be heard crying as they left the courtroom, while others hugged Ms Ross.
Bell's next trial will be held in Wellington.