Informal diminutive of Jonathan or John, from Hebrew Yohanan meaning 'God is gracious.'
Jonny is a variant spelling of Johnny, the English diminutive of John — one of the most durable personal names in the Western tradition, derived from the Hebrew Yohanan, meaning "God is gracious" or "Yahweh has shown favor." John entered European naming culture through the New Testament's multiple Johns — the Baptist, the Apostle, the Evangelist — and became so pervasive across Christian Europe that it eventually gave rise to a secondary language of nicknames: Jack, Ian, Sean, Giovanni, Johann, Jean, and the familiar American Johnny, the form that carries an essentially democratic, democratic-American character. The -y versus -ie distinction matters culturally: Johnny has historically appeared in American popular culture as slightly more formal, while Jonny with its single n and -y ending carries a somewhat more angular, contemporary edge.
Jonny Greenwood, the guitarist and composer of Radiohead and one of the most acclaimed film composers of his generation, has perhaps done most in recent decades to give the spelling a creative, intellectual cachet. Jonathan is frequently the birth certificate name behind both spellings — Jonny offering an informal daily-use version that sidesteps the biblical formality of the full name. John-derived names had a long stretch of supreme dominance in English — for much of the 16th through early 20th centuries, a substantial percentage of Englishmen were named John — before declining sharply in the late 20th century as parents sought distinctiveness.
Jonny as a standalone name rather than a nickname is genuinely uncommon, giving it the freshness of something familiar heard slightly differently. It carries the warmth and accessibility of the nickname register without the grown-up formality of Jonathan, making it a name that feels both approachable and subtly considered.