Jerry Lewis is expected to receive 30 years to life in prison as part of a plea deal.
"The defendant is guilty of two horrific homicides, and this office will recommend the maximum sentence of life in prison without parole," Suffolk County District Attorney Thomas Spota said.
In February, Lewis admitted he stabbed 21-year-old Shakeela Planter to death a week before Christmas in 2011.
He then fatally beat her 2-year-old son Jaiden, wrapped the boy's body in plastic and put him in the freezer of Planter's Bay Shore apartment.
Lewis was arrested in Laurel, Maryland, on Christmas Eve in 2011, when he turned himself in to police.
Lewis suspected Planter of dating other men.