Born in Cleveland, Ohio, to a Viennese mother and Jewish stepfather, Ronald Brooks (R.B.) Kitaj became a noted painter and printmaker whose subjects were realistic and abstract figure and genre. Many of his works were inspired by his political ideas and by reactions to stories he heard from his family about the Nazis during World War II.
At an early age, he developed a compassion for persons less fortunate and became dedicated to socialism, which had a lasting effect on his life and work. He was stirred by discussions about the Republican cause in the Spanish Civil War and by the events during World War II in Europe, especially as recollected by his parents and his Jewish step-grandmother, who moved in with his family.
Kitaj also learned much on various voyages as a merchant seaman in Latin America and through attending art schools, first in 1950 at the Cooper Union for the Advancement of Science and Art in New York, and in 1951 to 1952 at the Akademie der Bildenden Knste, Vienna, under Albert Paris von Gtersloh.
After his marriage in 1953 to Elsi Roessler, a fellow American student whom he had met in Vienna, he made his first extended visit to the Catalan port of San Felu de Guixols, and he continued to return their regularly over the next 30 years.
From 1955 to the end of 1957 he served in the American Army near Fontainebleau, where he drew pictures of the Russian tanks and installations for war games.Kitaj was recognised as being one of the world's leading draftsmen, almost on a par with, or compared to, Degas. Indeed, he was taught drawing at Oxford by Percy Horton, himself a pupil of Walter Sickert, who was a pupil of Degas; and the teacher of Degas studied under Ingres. His more complex compositions build on his line work using a montage practice, which he called 'agitational usage'. Kitaj often depicts disorienting landscapes and impossible 3D constructions, with exaggerated and pliable human forms. He often assumes a detached outsider point of view, in conflict with dominant historical narratives. This is best portrayed by his masterpiece "The Autumn of Central Paris" (1972–73), wherein philosopher Walter Benjamin is portrayed, as both the orchestrator and victim of historical madness. The futility of historical progress creates a disjointed architecture that is maddening to deconstruct. He staged a major exhibition at Los Angeles County Museum of Art in 1965, and a retrospective at the Hirshhorn Museum in Washington D.C. in 1981. He selected paintings for an exhibition, "The Artist's Eye", at the National Gallery, London in 1980.
In his later years, he developed a greater awareness of his Jewish heritage, which found expression in his works, with reference to the Holocaust and influences from Jewish writers such as Kafka and Walter Benjamin, and he came to consider himself to be a "wandering Jew". In 1989, Kitaj published "First Diasporist Manifesto", a short book in which he analysed his own alienation, and how this contributed to his art. His book contained the remark: "The Diasporist lives and paints in two or more societies at once." And he added: "You don't have to be a Jew to be a Diasporist."
A second retrospective was staged at the Tate Gallery in 1994. Critical reviews in London were almost universally negative. British press savagely attacked the Tate exhibit, calling Kitaj a pretentious poseur who engaged in name dropping. Kitaj took the criticism very personally, declaring that “anti-intellectualism, anti-Americanism, and anti-Semitism” had fueled the vitriol. Despite the bad reviews, the exhibition moved to the Metropolitan Museum of Art in New York and afterwards to the Los Angeles County Museum in 1995. His second wife, Sandra Fisher died of a brain aneurysm in 1994, shortly after his exhibition at the Tate Gallery had ended. He blamed the British press for her death, stating that “they were aiming for me, but they got her instead.” David Hockney concurred and said that he too believed the London art critics had killed Sandra Fisher. Kitaj returned to the US in 1997 and settled in Los Angeles, near his first son. The "Tate War" and Sandra's death became a central themes for his later works: he often depicted himself and his deceased wife as angels.
Kitaj was one of several artists to make a post-it note in celebration of 3M's 20th anniversary. When auctioned on the internet in 2000, the charcoal and pastel piece sold for $925, making it the most expensive post-it note in history, a fact recorded in the Guinness Book of World Records. Kitaj was elected to the Royal Academy in 1991, the first American to join the Academy since John Singer Sargent. He received the Golden Lion at the Venice Biennale in 1995. He staged another exhibition at the National Gallery in 2001, entitled "Kitaj in the Aura of Cézanne and Other Masters".
In September 2010 Kitaj and five British artists including Howard Hodgkin, John Walker, Ian Stephenson, Patrick Caulfield and John Hoyland were included in an exhibition entitled The Independent Eye: Contemporary British Art From the Collection of Samuel and Gabrielle Lurie, at the Yale Center for British Art.