In 1946, he moved with his family to New York City, where his father, Aurelio Guidi, found work as an opera singer under the stage name Nino D'Aurelio.

His most famous songs of the period are : "Julia" (1958), "Boccuccia di rosa" ("Pink Lips", 1958), "Love in Portofino" (1959), "Lettera a Pinocchio" (1959), "Monte Carlo" (1961).

In 1962 Dorelli appeared on The Ed Sullivan Show and sang his smooth ballad "Love in Portofino" and "You're the Top" with Connie Francis and Johnny Hallyday.

Some songs of this periods are "Speedy Gonzales" (1962), "Era settembre" (1964), "Probabilmente" (1965), "Al buio sto sognando" (1966), "Solo più che mai" ("Strangers in the Night", 1966), "Arriva la bomba" (1967), "I Think of You" (1972).

His greatest success was the musical Aggiungi un posto a tavola, which was also performed at the Adelphi Theatre in London's West End in an English version entitled Beyond the Rainbow in 1978.