Baby P died after months of abuse despite being monitored by officials
The Attorney General has decided prison sentences imposed on the three people convicted over the death of Baby Peter were not unduly lenient.
Baby Peter's mother was sentenced to at least five years, her boyfriend was jailed for 12 years, and their lodger was sentenced to at least three years.
Lady Scotland said there was "no realistic prospect" of the Court of Appeal increasing those sentences.
Peter was found with horrific injuries in Haringey, north London, in 2007.
The case papers, the law and the relevant sentencing guidelines were reviewed by Baroness Scotland before she deciding against referring their tariffs to the Court of Appeal.
Peter's mother and lodger Jason Owens were given indefinite sentences. She must serve at least five years and Owens at least three years.
The boyfriend was given 12 years over Peter's death and life for raping a two-year-old girl. He must serve a minimum of 10 years.
The Attorney General said: "It was clear to me that the judge, who had heard all of the evidence, fully appreciated the gravity of these terrible offences and took into account all of the relevant factors.
"I believe that the sentences fall within the range that it was reasonable for the judge to have imposed and there is no realistic prospect that the Court of Appeal would increase the sentences if I referred them."
She said the life and indefinite sentences handed down by the judge were "entirely merited".
The three defendants would only be released if and when they no longer presented a risk to the public, and children in particular, she stressed.
The decision comes as it emerged the boyfriend of Baby Peter's mother is to appeal against the convictions for the role he played in the boy's death and the rape of a two-year-old girl.