Alexander Emil Caiola was born on September 7, 1920, in Jersey City, New Jersey, the son of Emil Caiola, a barber, and Genevieve Esposito. He first wanted to be a singer, and his father steered him toward instruments, first the banjo and then the guitar. By eleven he was a recognized prodigy, studying with Anthony Antone in New York and Peter Milano in Jersey City, and in later years with Harry Volpe. As a boy he worked from Eddie Lang's guitar method and admired Lang and Bing Crosby. At sixteen he sang and played on a children's radio program, Sally and Sam, alongside the guitarist Tony Mottola, who became a lifelong colleague and pushed him to master new techniques.

During World War II Caiola served in the United States Marine Corps, playing trumpet in the 5th Marine Division Band, a unit that also included Bob Crosby, and he served as a stretcher bearer at the Battle of Iwo Jima. He came home to study at the New Jersey College of Music on the GI Bill and in 1946 joined CBS in New York as a staff musician, a post he held until 1956. At the network he played on Arthur Godfrey's Talent Scouts, Ed Sullivan's Toast of the Town and The Jackie Gleason Show, under the conductor Ray Bloch.

He left CBS because freelance work paid more and offered more variety, and for the next fifteen years he was one of the first-call guitarists in New York, in a circle of studio players that Vintage Guitar's obituary calls the Manhattan Guitar Club: Mottola, Bucky Pizzarelli and Mundell Lowe. The jazz discographer's listing of Atlantic Records sessions alone puts him on at least 21 dates between January 1957 and May 1959, behind Ivory Joe Hunter, Chuck Willis, LaVern Baker, Ruth Brown, Bobby Short, Bobby Darin and King Curtis, and on banjo as well as guitar. On December 19, 1958, with Hank Jones at the piano, he was in the orchestra that recorded Darin's "Mack the Knife." His obituaries and published session listings also place him on sessions for Frank Sinatra, Tony Bennett, Barbra Streisand, Johnny Mathis, Neil Sedaka, Paul Anka, Del Shannon, Ben E. King and Simon and Garfunkel, and Vintage Guitar reports that he played on Buddy Holly's New York sessions of 1958.

The records under his own name that jazz listeners value most are the two Savoy albums of 1955 and 1956. Produced by Ozzie Cadena and recorded at Rudy Van Gelder's studio in Hackensack, New Jersey, Deep in a Dream (Savoy MG 12033) paired Caiola with the trumpeter and flugelhorn player Bernie Privin, the pianist Hank Jones, the bassist Clyde Lombardi and the drummer Kenny Clarke, and Serenade in Blue (MG 12057) kept Jones, Lombardi and Clarke, adding the reed player Romeo Penque and, on four tracks, the pianist Ronnie Ball. Both are standards and original pieces played in a quiet, chamber-sized style. His sideman work in the same years included Howard McGhee's Life Is Just a Bowl of Cherries (Bethlehem, February 1956) with Herbie Mann among the woodwinds, Morgana King's debut For You, For Me, For Evermore (EmArcy, 1956), a Willis Jackson date in February 1957 with Quincy Jones and Kenny Burrell, Ruth Brown's April 1957 session with Percy Heath and Connie Kay, Ralph Burns's Very Warm for Jazz (1958) with Al Cohn, Zoot Sims and Urbie Green, and a Don Redman album with Coleman Hawkins and Harry Edison.

In 1960 he signed with United Artists, where he recorded for the next decade, and the label turned him into a recording star. His instrumental versions of the theme from the film The Magnificent Seven and the television theme "Bonanza" reached No. 35 and No. 19 on the Billboard Hot 100 in 1961, with a large-orchestra backing arranged and produced by Don Costa. The only other chart entry was "From Russia with Love" in 1964. The success of "Bonanza" led to commercial sessions for Marlboro, and Vintage Guitar's obituary counts more than sixty albums as a leader, over fifty of them for United Artists, including western television themes, spy and film themes, Italian, Spanish, Hawaiian and country records, and an album called Tuff Guitar that covered "A Hard Day's Night" and "Tequila." Beside these sat the jazz-flavored exceptions, such as Guitars Guitars Guitars (1960), which hands swing-era standards like "A String of Pearls" and "King Porter Stomp" to a section of New York guitarists including Mottola, Pizzarelli and Barry Galbraith, and Cleopatra and All That Jazz (1962), credited to Al Caiola and the Nile River Boys, whose band included the trumpeter Clark Terry, the pianist Dick Hyman and the bassist George Duvivier. He also played for Lena Horne on her 1962 RCA album Lena on the Blue Side.

At the urging of the Ashley-Famous agency he played Las Vegas in the 1960s, and he ran his own publishing firm, Alpane Music. After leaving United Artists he continued on smaller labels through the 1970s and 1980s, with Spanish-themed and Italian instrumental albums, and he appears on guitar on Lionel Hampton Presents: Woody Herman (1977), a quintet-plus-percussion record with Woody Herman, Lionel Hampton, Roland Hanna and George Mraz. He toured with Steve Lawrence and Eydie Gormé for 28 years, living in South Palm Beach, Florida, and later moved back to New Jersey to be near family. Epiphone issued an Al Caiola Standard model in his name. Al Caiola passed away on November 9, 2016, in Allendale, New Jersey, at the age of 96. He was survived by his wife, Rosalie, a son, Alexander Jr., a daughter, Sandra Ayres, four grandchildren and four great-grandchildren.

Caiola was a studio guitarist first and a bandleader second, and the pop and television-theme side of his output is the larger part of it: the records for United Artists are arrangements of hits, film cues and national folk songs played over a lush orchestra, and AllMusic files him under easy listening with jazz as a second genre. His own sound was a light, liquid single-note line, and a pianist who worked with him remembered him as comfortable in jazz, rock and roll and classical settings. His models were Eddie Lang and Tony Mottola. The jazz side is real but narrower. The Savoy albums of 1955 and 1956 are cool and restrained and, as one reviewer of their 2016 reissue put it, closer to romantic mood music than to hard swinging, while the date sheets show him as a reliable rhythm and solo guitarist and banjoist for Atlantic, Bethlehem, EmArcy, Decca and Urania sessions led by working jazz players. He is best understood as a bridge figure between the New York jazz rhythm-section world of the 1950s and the instrumental pop of the 1960s.