In 1965, he briefly filled in for Nick Massi (who was Calello's replacement in The Four Lovers five years earlier but had abruptly quit the band) while the band prepared Joe Long to take the role on a permanent basis.

He has worked and recorded with Barbra Streisand, Frank Sinatra, Roberto Carlos, Neil Diamond, Al Kooper, Bruce Springsteen, Jane Olivor, Laura Nyro, Liza Minnelli, Engelbert Humperdinck, the Cyrkle, Jimmy Clanton, Ray Charles, Deana Martin, Natalie Cole, Bobby Vinton, Janis Ian, Barry Manilow, Juice Newton, Red Rider, Nancy Sinatra, the Highwaymen, Shirley Ellis, Deborah Allen, and many others.

Calello was the conductor and responsible for the string arrangements on Springsteen's "Jungleland" from the album Born to Run.

[5] Some of his hits include “Sweet Caroline” by Neil Diamond, “Native New Yorker” by Odyssey, “My Heart Belongs to Me” by Barbra Streisand, and “After the Lovin'” by Engelbert Humperdinck.

[6] He has also composed film music, including the scores to Who Killed Teddy Bear (1965) and The Lonely Lady (1983).