Seven of the charges he was guilty of were doing an act likely to prejudice service discipline, which related to Manning having sex with two recruits.
He was also found guilty of indecently assaulting a third recruit.
He was found not guilty of five charges relating to sexual violation and inducing a sexual connection by threat.
In the High Court at Wellington today, Justice David Collins, Judge John Billington and Judge David McGregor reduced his sentence to three months detention, followed by his dismissal from the army.
Earlier today, Manning's lawyer Paul Murray argued the original sentence was manifestly excessive.
He said the judges might be able to "step back" from the dismissal aspect of the sentence.
There were a number of factors in Manning's favour, including his guilty pleas, an offer of restorative justice and previous good character, Mr Murray said.
There was also remorse shown following the indecent assault, with Manning approaching the victim the following day and apologising, he said.
Mr Murray also noted Manning was awarded the Distinguished Service decoration in the 2009 New Year Honours list because of an incident in Afghanistan where he intervened and halted a violent incident between two local police officers.
For the prosecution Captain Matt McGrath said Manning was dismissed because there was a fundamental breach of trust.
"It would be intolerable for Bombardier Manning to remain in the service," he said.
Manning had "flouted the rules" that were put in place to protect soldiers under his care.
Regarding the charge of indecent assault, Captain McGrath said Manning held a position of trust, at the time was wearing only his underwear, was supposed to have been in charge of a platoon and continued to attempt to kiss his victim when she had already declined his advances.
Manning was not at today's hearing.
