The name Alfonzo derives from the Germanic name Alfonso, which originated from the medieval Spanish and Portuguese form of the Visigothic name Adefonsus. Adefonsus itself is composed of the Gothic elements "ath" meaning "noble" and "funs" meaning "ready" or "eager."

The name Alfonzo emerged as a variation of the Spanish and Portuguese Alfonso during the Middle Ages. It was particularly prevalent in regions formerly under Moorish rule, such as Andalusia and parts of modern-day Spain and Portugal. The earliest known recorded use of the name Alfonzo dates back to the 9th century CE.

One of the most notable historical figures bearing the name Alfonzo was Alfonzo X, also known as Alfonso the Wise (1221-1284). He was a renowned king of Castile and León, remembered for his patronage of scholarship and the promotion of the Castilian language through his literary works.

Another significant bearer of the name was Alfonzo de Zamora (c. 1285-1349), a Spanish Jewish philosopher and polemicist who engaged in religious debates with Christian scholars during the 14th century.

In the 15th century, Alfonzo V of Aragon (1396-1458), also known as Alfonso the Magnanimous, was a prominent ruler of the Crown of Aragon and the Kingdom of Naples. He was renowned for his military conquests and his support of Renaissance humanism.

During the 16th century, Alfonzo Ferrabosco (c. 1543-1588) was an Italian composer and instrumentalist who served at the court of Queen Elizabeth I in England.

In the 17th century, Alfonzo Chacón (c. 1530-1599) was a Spanish Dominican friar and theologian who played a significant role in the Catholic Reformation and the Council of Trent.