Jesus called Philip to be a disciple (John 1:44) as he (Jesus) was leaving Bethany after being baptized by John (John 1:28). Philip's immediate response was to go and find Nathanael and tell him "We have found the one Moses wrote about in the law, and about whom the prophets also wrote Jesus of Nazareth, the son of Joseph."
We learn most about Philip from the Gospel of John, but his name appears in all the synoptic gospels as well (Matthew 10:3, Mark 3:18, Luke 6:14). He was from Bethsaida, in Galilee (John 12:21). When Jesus needed to feed the five thousand (John 6:5-7) he rhetorically asked Philip for suggestions and Philip's answer was practical, if uninspired. Later when Philip had to take a message to Jesus (John 12:22) he asked Andrew to accompany him, perhaps indicating the awe which he felt in the presence of the Lord. He took an active part in the disciples' discussions with Jesus (John 14:8) but, like most of the disciples, was perhaps a bit slow in understanding what Jesus was telling them (John 14:9).
Philip the apostle should not be confused with Philip the evangelist (Acts 21:8), even though they both displayed an instinct for evangelism. They knew each other though Philip, as one of the apostles, prayed for and laid hands on Philip the evangelist (Acts 6:6) at the start of the latter's ministry.
There is little written about Philip the apostle's life after Jesus died. Polycrates of Ephesus, in a letter written about 190, refers to his grave as being in Hieropolis. There is some debate about whether that might actually be the grave of Philip the evangelist because the letter mentions three daughters, which could be the daughters mentioned in Acts 21:9. The remains of whichever Philip it was were later moved first to Constantinople and then to the church of the Dodici Apostoli in Rome, where they are now identified as the remains of the apostle.