The jury heard closing arguments on Tuesday and began deliberating on Wednesday before delivering their verdict late Thursday afternoon.
McNeil's attorney, Bryan Collins, had told jurors that she did not intentionally kill her son, but she did hide his body.
During the trial, the jury watched a video tape of McNeil re-creating what she said was the accident that killed her son - she said Gross hit his head on a coffee table.
"He was just jumping and then he came like this, and he came down and it just, boom, boom like that," said McNeil on the tape.
The defense said McNeil was too scared to call for help because she had admitted to others she'd abused him before and was afraid people would think she killed him. So, she admittedly hid his body.
However, prosecutors claimed McNeil abused the 19-month-old for several weeks leading to his death, then stuffed his body in trash bags, placed him in a plastic bin with bleach soaked sheets to cover the smell, and left the bin in her closet while she went on with her life.
"She has casual sex with a virtual stranger who she met a week before while her dead baby is in the closet," said Assistant District Attorney Melanie Shekita to the jury. "She's worried about what she's going to wear to a concert all the while she's pouring bleach on a child that she's killed in her closet."
Jurors also heard phone calls during the trial between McNeil and her family, which prosecutors said confirmed police suspicions that McNeil wanted her then-2-year-old daughter, but not her son.
"I really don't, I really don't want any more kids," McNeil said in a phone conversation. "All I want is her, that's it."
After the verdict, McNeil was escorted from courtroom and taken to the Wake County Jail.