The surname Ambrogi and its numerous variants belong to one of the broadest and oldest onomastic groups in Italy. Its origin is anthroponymic and goes back to the Latin personal name Ambrosius, an adaptation of the Greek Ambrosios, meaning "immortal". This name spread early on the peninsula thanks to Christianity and, in particular, to the cult of Saint Ambrose of Milan, one of the most influential figures of the late antique Church.

According to E. De Felice, the surname is widely spread throughout Italy, with a great variety of regional forms. In the south the full and patronymic forms such as Ambrosio or D'Ambrosio predominate; in the north the forms in -i and the abbreviated ones are more frequent; in Tuscany variants in -g- such as Ambrogi appear; while in Lombardy the forms in -gg- and other reductions are common.

The great antiquity and diffusion of the name Ambrogio explains the diversity of derived surnames. On the one hand, full and patronymic forms developed such as Ambrogio, Ambrogi, Ambrosi, Ambrosio, Ambrosini, Ambrosino, among others, which preserve the direct link with the original name. On the other, abbreviated forms arose by aphaeresis (loss of the initial syllable), such as Brogi, Broggi, Brosi, typical of northern Italy.

There are also more evolved variants such as Roggio or Sbroggio, the result of dialectal and phonetic processes peculiar to certain regions. All these forms do not constitute independent lineages, but form part of the same onomastic system derived from the name Ambrogio, fixed in various ways according to the areas.

Taken together, Ambrogi and its variants reflect a common origin linked to a name of strong symbolic value —"immortal"— whose religious and cultural diffusion gave rise to one of the richest and most widespread families of surnames in Italy.