Jesus promises the overcomers in the church at Philadelphia that He will set them up as pillars of His temple and inscribe them with a triple name – the name of God, the name of new Jerusalem, and Jesus’ own “new name” (Revelation 3:12).
New names are common in the Bible. The Lord Himself adopts new names as He unveils Himself progressively in time: El Shaddai, Elohim, Yahweh, Yahweh Zebaoth, Adonai Yahweh. And the covenant partners He selects often get new names and new identities: Abram becomes Abraham and Sarai Sarah; Jacob becomes Israel; Daniel and his friends get Babylonian names, and Saul becomes Paul.
Though the phenomenon of a new name is common, the phrase “new name” is not. Apart from Revelation 3:12 (and 2:17), it is used only in Isaiah 62:2. There Israel is promised a new name, one that is spelled out in the following verse: From “Forsaken” and “Desolate” to “My delight is in her” and “Married.” She takes a new name as Yahweh her Bridegroom takes Israel as His Bride (vv. 4-5).
Which makes sense in the context of Revelation 3:12 too. Jesus is the Bridegroom, the glorified Lover, who comes for His bride. At the end of Revelation, that Bride appears, and she and Jesus both take the name “Married.”