The 21-month-old, nicknamed Sasha, had respiratory issues but was released on Wednesday morning.
"Sasha got home today and is feeling much better after being hospitalized on Tuesday night with respiratory problems," a rep for Liev told the mag.
Liev flew home to New York on Tuesday to be with his family, a trip that Access Hollywood has learned was already planned – he is due back on the set of "Salt," and is thought to have arrived home before his son's illness occurred.
The trip caused the actor to miss the Los Angeles premiere of his latest film, "X-Men Origins: Wolverine," in which he stars as the title character's arch-nemesis, Sabretooth.
Liev and Naomi have two children together; Alexander and his younger brother, Samuel, who was born in December of last year.