Of his eight sons two at least acquired fame as musicians: Pietro Carlo Guglielmi (1763-1827), a successful imitator of his father's operatic style, and Giacomo Guglielmi, an excellent singer.
Af hans otte sønner erhvervede mindst to berømmelse som musikere: Pietro Carlo Guglielmi (1763-1827), en succesfuld imitator af sin faders operatiske stil og Giacomo Guglielmi, en fremragende sanger.