The victim, Bernadette Moran (37), is the wife of the Donegal football team doctor, Kevin Moran.
She was in Dublin with her three children for an All-Ireland quarter-final match in Croke Park when Christopher Coakley (21) pulled her out of her jeep and tried to drive away.
He ignored her pleas to let her get her child from the backseat but the woman managed to flee with the child as Coakley was distracted by trying to work the jeep's controls.
Judge Desmond Hogan sentenced him to three years which is to run alongside a three-year sentence he is serving for a firearms offence. This was backdated to December 5 last when he was taken into custody.
Coakley, of Belvedere Place, pleaded guilty at Dublin Circuit Criminal Court to hijacking the jeep at Mountjoy Square on August 5, 2012.
The court heard he has 92 previous convictions and during his teens he was up before the Children's Court "two or three times a week".
The judge said he was not going to impose a consecutive sentence as Coakley "is still a young man" but warned that this shouldn't be seen as a precedent. He imposed 12 months post-release supervision.
Garda Carl Byrne told prosecuting counsel Martina Baxter that Ms Moran had stopped the jeep and was waiting as two of her children played in the park.
She looked in the rear-view mirror and saw someone running towards her. Coakley then pulled open the door and told her to "get the f*** out".
Ms Moran was able to grab her phone before getting out of the jeep.
Coakley got in the driver's seat and was trying to operate the gears as Ms Moran pleaded with him to let her get the nine-year-old from the backseat.
Coakley was trying to accelerate with the handbrake on and there was black smoke coming from the exhaust. Ms Moran used the opportunity to get the child out, seconds before the jeep sped off.
The vehicle was found abandoned shortly afterwards and a fingerprint on the door led to Coakley's arrest the next month.
Coakley's mother, Paula Johnson, said she is "so ashamed and sorry for the woman and her children".
She tearfully told the court her son needs residential treatment for his drug abuse because "this is no life for anyone."