The boy, who cannot be named for legal reasons, went on trial at Sheffield Crown Court accused of attempted murder last month, but jurors found him guilty of the lesser charge of wounding with intent.
The attack took place in the early hours of March 18 this year, when the boy held a knife to the throat of a woman walking in Gibbons Drive, Norton, and told her to: 'Show me what you've got'.
He stabbed her twice and when she tried to escape, the boy chased after her and stabbed her a further three times.
Ian West, prosecuting, told Sheffield Crown Court how the woman suffered a number of serious injuries including a wound to her heart and a punctured lung that resulted in two hospital admissions.
"The complainant has had her self confidence diminished, and the scarring [from the attack] has very adversely affected her mental state," said Mr West.
He added: "Her whole life has been affected."
At the opening of the trial, jurors were told how the victim believed there may have been a sexual motive for the attack because the boy continued to ask her to 'show me what you've got,' even after she offered him her purse, mobile phone and car keys.
The Recorder of Sheffield, Judge Jeremy Richardson QC, said he suspected the boy may have had a sexual motive for attacking his victim but said he could not be satisfied so that he was sure.
Judge Richardson said he would therefore sentence the boy based on his claim that his motive for attacking the woman was robbery.
The school boy pleaded guilty to having a bladed article at the beginning of the trial. He also offered a guilty plea to the charge of wounding with intent at this time, but the Crown Prosecution Service rejected the plea and put him on trial for attempted murder.
Defending, Gordon Stables, said: "This is a classic case of an impulsive decision taken by a child or young person...he does appear to be genuinely and honestly remorseful."
Mr Stables added: "The Youth Justice Service seem very keen that the sentence passed is ultimately one that is less than five years, in order for them to maximise the choices of rehabilitation for this young man and so they can keep him within the current establishment where he's doing so very well."
Judge Richardson told the court he believed the boy could be rehabilitated, and following Mr Stables' mitigation, reduced the boy's custodial sentence from one of five-and-a-half years to one of five years in order to prevent him from being sent to an adult prison when he turned 18.
"What you did was exceptionally serious. You had a knife, you stabbed her. She has suffered grievous injuries. Her life has been massively affected by what you did," Judge Richardson told the boy.