St Barnabas' story appears in the Acts of the Apostles, and St Paul mentions him in some of his epistles. According to Acts 4:36, he was a Cypriot Jew, and he was named as an apostle in Acts 14:14. He and St Paul undertook missionary journeys together and defended Gentile converts against those who said converts should become Jews first. In the years AD46-48, they travelled together preaching the gospel, and they participated in the Council of Jerusalem (c. AD49). Barnabas is usually identified as the cousin of Mark the Evangelist.

Little is known of Barnabas’ subsequent career. He was still living and labouring as an Apostle in AD56 or 57, when Paul wrote 1 Corinthians, in which it is stated that Barnabas, like Paul, earned his own living. The reference indicates that the friendship between them remained close. When Paul was a prisoner in Rome (AD61-63), Mark was attached to him as a disciple, which is generally regarded as an indication that Barnabas was no longer living by then (Colossians 4:10).

Although the date, place, and circumstances of his death are historically unverified, Christian tradition holds that Barnabas was martyred at Salamis in Cyprus. According to legend, certain Jews, affronted by his success, attacked Barnabas as he was debating in the synagogue, dragged him out, and stoned him to death.

The History of the Cyprus Church, tells us that, in 478, Barnabas appeared in a dream to the then Archbishop of Cyprus, Anthemios, and revealed to him the place of his sepulchre beneath a carob-tree. The following day Anthemios found the tomb and inside it the remains of Barnabas with a manuscript of Matthew's Gospel on his breast. Anthemios then placed the venerable remains of Barnabas in a church which he founded near the tomb. Excavations near the site of a present-day church and monastery, have revealed an early church with two empty tombs, believed to be that of Barnabas and Anthemios.

St. Barnabas is venerated as the patron saint of Cyprus and the founder of the Cypriot Orthodox Church. He is also considered a patron saint in many other places in the world, including Milan. On the island of Tenerife, Barnabas was invoked in historical times as patron saint and protector of the island's fields against drought.