The "Frasier" star and his wife, Kayte Grammer, welcomed son Kelsey Gabriel Elias Grammer in Los Angeles on Tuesday, according to Grammer's rep, Stan Rosenfield.
The "magnificent" little guy clocked in at 8:28 a.m., weighed in at 8 pounds 2 ounces, and measured 20.5 inches.
"We are blessed and excited to have this lovely young man join our family -- he is magnificent," the family said in a statement.
The 59-year-old Emmy and Golden Globe winner said that his son would go by his middle name Gabriel "as there is a tradition in our family of going by our middle names." (Indeed, the actor's full name is Allen Kelsey Grammer.)
Grammer, who will next appear in FX's "Partners" and recently joined Twitter to help its grammar problem, has four children from his previous relationships: daughter Spencer, 30, with first wife Doreen Alderman; daughter Greer, 22, with his ex-girlfriend, makeup artist Barrie Buckner; and daughter Mason Olivia, 12, and son Jude Gordon, 9, whom he had via surrogate with his third wife, "The Real Housewives of Beverly Hills" alum Camille Donatucci.
The TV star and producer is already a grandfather to Spencer's son, Emmett Emmanuel, whom she welcomed in October 2011, according to the Daily Mail.
Entertainment Tonight was first to report the news and obtain photos of the Grammers with their newest addition.