The girls, who cannot be named for legal reasons, took a 3-year-old girl from Newcastle's Primark store on April 13 in an act which prompted a huge police hunt across the city.
Aged 13 and 14, the teens admitted kidnapping at a previous hearing and were sentenced today at Newcastle Crown Court.
Mr Justice Globe, who was the junior prosecutor in the James Bulger case more than 20 years ago, passed the sentence.