Insiders told the publication that the 2-year-old was rushed to an LA based hospital on Thursday.
His celebrity parents were with him while he remained in hospital overnight.
Kim and Kanye reportedly took turns looking after their little one.
Saint was released on Saturday following days of treatment and observation.
The toddler is now recovering at home with his fam.
Kim took to Insta to confirm the news and thank the hospital for looking after her bubba.
"My precious baby boy is so strong!" She captioned a pic of her son.
"After spending three nights in the hospital & seeing my baby get multiple IV’s and hooked up to oxygen machines, our end of year was challenging. Pneumonia is so scary."
She adds: "I just want to thank every nurse & doctor out there who works so hard around the clock. We are so grateful for you all! He’s home and all better. He’s so resilient I’m sure he will still say the ambulance ride was cool! My strong Saint 👼🏽"