Peter names himself
The opening line gives the clearest answer. The author introduces himself as Peter, an apostle of Jesus Christ, and writes to believers scattered across several regions of Asia Minor, in what is now Turkey (1 Peter 1:1). So the book has long been known as 1 Peter because it presents itself as a letter from the apostle Peter.
Peter writes as someone who knew Jesus personally and had been sent to bear witness to him. He does not begin by drawing attention to his own achievements. Instead, he points struggling Christians towards God's mercy, a living hope, and an inheritance that cannot fade away (1 Peter 1:3-4).
Peter, an apostle of Jesus Christ, to the strangers scattered throughout Pontus, Galatia, Cappadocia, Asia, and Bithynia,
Which Peter was he?
This was Simon Peter, the Galilean fisherman Jesus called while he was working with his brother Andrew near the Sea of Galilee (Mark 1:16-18). Jesus gave Simon the name Peter, and Peter became one of the Twelve disciples. He saw Jesus' ministry closely, including moments of great faith and moments when he failed badly.
Peter famously denied knowing Jesus during the night of Jesus' trial. Yet after the resurrection, Jesus met him, challenged his love, and gave him a pastoral task of caring for his people (John 21:15-17). That history brings a quiet depth to 1 Peter. Its author knows that failure is real, but he also knows Christ restores people.
After Jesus' ascension, Peter openly spoke about Jesus in Jerusalem and became a leading witness to the resurrection (Acts 2:14). The confidence of 1 Peter is not the confidence of someone who never struggled. It is the confidence of a man who had received mercy.
He did not write entirely alone
Near the end of the letter, Peter says that he wrote through Silvanus, whom he describes as a faithful brother (1 Peter 5:12). This may mean Silvanus helped carry, compose, or prepare the letter, as was common with letters in the ancient world. It does not replace Peter as the named author. Peter still speaks of the letter as his own testimony and exhortation.
Peter also sends greetings from a church described as being in Babylon, along with Mark (1 Peter 5:13). Whatever details we may wish we knew, the letter keeps its focus on its readers: stand firmly in God's grace while living as faithful people in a world that may not understand them (1 Peter 5:12).
Why the author matters
Knowing Peter's story helps us hear the letter well. He writes to Christians facing grief, pressure, and hostility, yet he calls them to hope and holy living (1 Peter 1:6-7; 1 Peter 1:15-16). He had seen Jesus suffer, die, and rise again. He knew that hardship was not proof that God had abandoned his people.
Read 1 Peter with that in mind. This is an apostle urging ordinary believers to trust God, love one another, and keep doing good even when life is costly (1 Peter 3:14-15). Peter's message is steady and personal: God's grace can hold you.