Onement, I is an Abstract Expressionist Oil on Canvas Painting created by Barnett Newman in 1948. It lives at the MOMA, Museum of Modern Art in New York.

Newman saw Onement I as a breakthrough in his work. It features the first full incarnation of what he later called a "zip," a vertical band of color. This motif would play a central role in many of his subsequent paintings. The painting's title is an archaic derivation of the word "atonement," meaning, "the state of being made into one."

For Newman, Onement is viewed as a breakthrough that would carry through to much of his later work. This work features the first use of the “zip”, a vertical line of orange that both separates and unites either red side of this piece. The title, Onement, is said to have been influenced by the medieval term which means ’to unite’.

Newman proclaimed Onement, I to be his artistic breakthrough, giving the work an importance belied by its modest size. This is the first time the artist used a vertical band to define the spatial structure of his work. This band, later dubbed a "zip," became Newman's signature mark.