Valtýr Pétursson was a pioneer of Icelandic abstract art, a productive painter, an important art critic and an active participant in artists’ unions and groups. Valtýr was the only son of Þórgunn Árnadóttir and Pétur Einarsson, teachers in Grenivík. He lost both his parents at an early age, but grew up in Reykjavík with his maternal sister Gunnhildur Árnadóttir and Ólafur Guðmundsson, a shipowner.

     At the age of 16, he went to sea and was a sailor for the next 9 years, in addition to various other activities, including he was a truck operator at the British airport construction in 1941. Valtýr began drawing and painting early, studied woodcarving with Geir Þormar in Akureyri as a child and attended Björn Björnsson's drawing school in Reykjavík from 1934–1936. Works by him from 1934–1937 have been preserved, oil paintings and also many ship drawings. No works by Valtý from the years 1939–1944 have been preserved as far as we know. He had a desire to become a writer and stories and fragments of stories from these years have been preserved.

     In 1944, Valtýr went to Providence to study business at the instigation of his foster father. He also began art studies with Hyman Bloom(en) in Boston, began to embrace mysticism and draw strange creatures and then made the decision to become an artist after a visit to the Museum of Modern Art in New York. From 1945 to 1949, Valtýr painted with great energy, including hand-illustrating Stein Steinar's poetry books with surrealist images, but then began to embrace abstract art more and more. Valtýr, Kjartan Guðjónsson and Jóhannes Jóhannesson invited Þorvald Skúlason, Nína Tryggvadóttir, Gunnlaug Scheving, Snorri Arinbjarnar and Tove and Sigurjón Ólafsson to participate in the September Exhibition, the first of four in total, 1947, 1948, 1951 and 1952. The exhibitions were very controversial and the artists were shouted at in the streets. In the spring of 1949, Valtýr settled in the Accademia di Belle Arti(en) in Florence, Italy. In the autumn, he went to Paris to visit museums and exhibitions in the capital of the arts. In the autumn of 1950, Valtýr held his first solo exhibition at Galleri Gizard in Paris. Valtýr was in Paris until the end of 1950/1951, but visited the city often throughout his life. At the September Exhibition of 1951, Valtýr exhibited the first large-scale painting to be shown in Iceland. In 1956, Valtýr studied mosaic making with Gino Severini(en) in Paris and was subsequently commissioned to create mosaic wall decorations in the new building of the Teachers' College at Stakkahlíð. Throughout his life, Valtýr held 29 solo exhibitions and participated in over 100 group exhibitions during his long career. Valtýr's paintings changed greatly over time, but it can be said that the seafaring spirit of his youth is reflected in most of the art movements he espoused, in mysticism, in geometry, in tassism and in figurative painting. Valtýr was the art critic for Morgunblaðið from 1952 until his death, and he left behind around 900 articles that appeared in the newspaper. He was treasurer of the Icelandic Association of Visual Artists from 1951–1969 and chairman from 1969–1973.

     In 2012 the Reykjavík Art Museum held an exhibition of Valtýr Pétursson’s works called "The Lyric Vision – Abstract-Expressionism in Icelandic Art, 1957-1970." Other notable exhibitions for Valtýr Pétursson were at Listasafn Islands - National Gallery of Iceland in Reykjavik in 2016, and at Reykjavík Art Museum and Safnahúsið in Reykjavik. In 2024 the National Gallery of Iceland included works by Pétursson at the exhibition "Looking Inward, Looking Outward: 140 years of the National Gallery of Iceland."

     The artist is represented in the Valtýr Pétursson Museum, National Gallery of Iceland, and Skissernas Museum, lund.