Mikaeel Kular had been "healthy, happy" normal child until he was attacked by Rosdeep Adekoya after a family day out in January this year.
Adekoya, 34, left him with more than 40 separate injuries and he died two days later. His mother then pretended he had gone missing, prompting a major search in and around Edinburgh before his body was found near a relative's home 25 miles away in Kirkcaldy, Fife.
Yesterday judge Lord Glennie told her sentencing hearing at the High Court in Edinburgh that what she did was cruel and inexcusable, though he accepted that the mother - who wiped away tears during the proceedings - had shown heartfelt remorse.
But he told Adekoya, whose guilty plea to culpable homicide and attempting to defeat the ends of justice was accepted by prosecutors after she had originally been charged her with murder, that "striking a child even once is bad enough. Striking him heavily and repeatedly with hand and fist when he was being sick again and again simply beggars belief."
Lord Glennie added: "Mikaeel was by all accounts a healthy, happy little boy. By your actions, however unintended, you have not only robbed Mikaeel of his young life but left a gaping hole in the lives of all who loved him."
Adekoya "lost her temper" when Mikaeel was repeatedly sick following a trip to an Edinburgh restaurant.
She smacked him and struck him on the body and head with a clenched fist. When her child was sick for a third time, she dragged him to the shower by his arms and "beat him heavily" on his back as he lay over the bath edge.
Over the next few days Mikaeel's condition worsened and he became listless but his mother did not take him to a doctor because of the bruising. He died on January 14 from injuries inflicted two days earlier.
The court heard that after discovering Mikaeel's lifeless body on the floor of their home in Ferry Gait Crescent, Adekoya put it in the suitcase and drove to woodland behind her sister's home in Dunvegan Avenue, Kirkcaldy, and covered it in branches.
She then dialled 999 to report him missing to police, sparking a major two-day search operation involving the emergency services and hundreds of local people who volunteered to help.
Mobile telephone masts recorded her journey across the Forth Road Bridge, undermining her statements to police, and she eventually broke down and took officers to his body.
Internet searches carried out by the mother, who had a history of depression and had attempted suicide in 2001, showed searches including "I find it hard to love my son" and "Why am I so aggressive with my son".
Defence lawyer Brian McConnachie, QC, told the judge: "There is no sentence your lordship can impose in this case which will be deemed sufficient by what appears to be an ill-informed mob who are no doubt at this moment waiting to express their outrage and indignation."
The lawyer attributed her actions immediately following the death of her son to "panic".
Lord Glennie told Adekoya: "There is no history of violence by you towards any of your children. That makes it all the more difficult to understand your actions. I do not suppose that you really understand why you did what you did."
Assistant Chief Constable Malcolm Graham, lead officer for Police Scotland on Major Crime and Public Protection, said the forces's thoughts were with the family. He added: "Mikaeel died through injuries sustained over a period of time inflicted by the very person who should have been there to care for him."
There was little contact between the children and Zahid Saeed, the father of Mikaeel and his twin sister, the court heard.