The prison term imposed on Vickrum Digwa, found guilty of killing Henry Nowak, has been sent to the Court of Appeal by the solicitor general under the Unduly Lenient Sentence programme.
Digwa, aged 23, received a life sentence with a minimum term of 21 years, handed down by Judge William Mousley KC at Southampton Crown Court on 1 June.
Solicitor General Ellie Reeves KC MP expressed her hope that the referral would contribute to achieving justice for Nowak’s family.
The 18-year-old student was repeatedly stabbed in the street using a 21cm (8in) blade, which Digwa said he was carrying due to his Sikh faith.
Nowak was initially detained and handcuffed by police during the incident on 3 December, before officers realised he had sustained serious injuries.
Digwa falsely informed officers at the scene that Nowak had assaulted and racially abused him.
In police body-worn camera footage, the student, from Chafford Hundred in Essex, repeatedly told authorities that he had been stabbed and was struggling to breathe.
The video, made public after the sentencing, sparked violent demonstrations in Southampton on 2 June.
In a statement, Reeves said: "This case horrified me, and I know that feeling is shared by the British public.
"It is right that difficult questions need to be answered about the way the police handled Henry's Nowak's murder, while my role is to review Digwa's sentence for his crimes.
"No sentence can ever undo the devastation that Henry's family have suffered, or fill the void left by his loss.
"But I hope this referral goes some way towards bringing them the justice they deserve."
Prime Minister Sir Keir Starmer, who earlier called it an "awful, shocking case", met with members of the Nowak family at Downing Street on 4 June.
Following the meeting, Sir Keir stated he had been "profoundly humbled" by the encounter and that Nowak deserved "a legacy that goes beyond this awful tragedy".
To date, 23 individuals have been charged in connection with the protests on 2 June, and 13 defendants have been imprisoned.
The Sikh Federation has urged the government to establish an inquiry into matters arising from the case, citing the carrying of blades and hostility directed towards Sikh community members since the murder.
Hampshire and Isle of Wight Constabulary is under investigation by the Independent Office for Police Conduct regarding the case.
An inquest into Henry Nowak’s death is scheduled to take place in Winchester in September 2027.