Arrow was born on 23 August 1921, in New York City. Arrow's mother, Lilian (Greenberg), was from Iași, Romania, and his father, Harry Arrow, was from nearby Podu Iloaiei. The Arrow family were Romanian Jews. His family was very supportive of his education. Growing up during the Great Depression, he embraced socialism in his youth. He would later move away from socialism, but his views retained a left-leaning philosophy.

He graduated from Townsend Harris High School and then earned a Bachelor's degree from the City College of New York in 1940 in mathematics, where he was a member of Sigma Phi Epsilon. He attended Columbia University, for his graduate studies. While there, he studied under Harold Hotelling, and was greatly influenced by him. He received a Master's degree in 1941. He served as a weather officer in the United States Army Air Forces from 1942–1946.

From 1946 to 1949 Arrow spent his time partly as a graduate student at Columbia and partly as a research associate at the Cowles Commission for Research in Economics at the University of Chicago. During that time he also held the rank of Assistant Professor in Economics at the University of Chicago and worked at the RAND Corporation in California. He left Chicago to take up the post of Acting Assistant Professor of Economics and Statistics at Stanford University. In 1951, he earned his Ph.D. from Columbia. He served in the government on the staff of the Council of Economic Advisers in the 1960s with Robert Solow. In 1968, he left Stanford for the position of Professor of Economics at Harvard University. It was during his tenure there that he received the Nobel Prize in Economics.

Arrow was a brother to the Economist Anita Summers, uncle to Economist and former Treasury Secretary and Harvard President Larry Summers, and brother-in-law of the late economists Robert Summers and Paul Samuelson. In 1947, he married Selma Schweitzer who died in 2015; they had two children: David Michael and Andrew Seth.

In 1951, Arrow presented the first and second fundamental theorems of welfare economics and their proofs without requiring differentiability of utility, consumption, or Technology, and including corner solutions.

Arrow was awarded the John Bates Clark Medal in 1957 and was elected a Fellow of the American Academy of Arts and Sciences in 1959. He was the joint winner of the Nobel Memorial Prize in Economics with John Hicks in 1972 and the 1986 recipient of the von Neumann Theory Prize. He was one of the recipients of the 2004 National Medal of Science, the nation's highest scientific honor, presented by President George W. Bush for his contributions to research on the Problem of making decisions using imperfect information and his research on bearing risk.

In other pioneering research, Arrow investigated the problems caused by asymmetric information in markets. In many transactions, one party (usually the seller) has more information about the product being sold than the other party. Asymmetric information creates incentives for the party with more information to cheat the party with less information; as a result, a number of market structures have developed, including warranties and third party authentication, which enable markets with asymmetric information to function. Arrow analysed this issue for medical care (a 1963 paper entitled "Uncertainty and the Welfare Economics of Medical Care", in the American Economic Review); later researchers investigated many other markets, particularly second-hand assets, online auctions and insurance.

In 1974, The American Economic Association published the paper written by Kenneth Arrow, General Economic Equilibrium: Purpose, Analytic Techniques, Collective Choice, where he states:

Arrow returned to Stanford in 1979 and became the Joan Kenney Professor of Economics and Professor of Operations Research. He retired in 1991. As a Fulbright Distinguished Chair, in 1995 he taught Economics at the University of Siena. He was also a founding member of the Pontifical Academy of Social Sciences and a member of the Science Board of Santa Fe Institute. At various stages in his career he was a Fellow of Churchill College, Cambridge.

Work by Arrow and Gérard Debreu and simultaneous work by Lionel McKenzie offered the first rigorous proofs of the existence of a market clearing equilibrium. For this work and his other contributions, Debreu won the 1983 Nobel Prize in Economics. Arrow went on to extend the model and its analysis to include uncertainty, the stability. His contributions to the general equilibrium theory were strongly influenced by Adam Smith's Wealth of Nations. Written in 1776, The Wealth of Nations is an examination of economic growth brought forward by the division of labor, by ensuring interdependence of individuals within society.

He has received honorary doctorates from the University of Chicago (1967), the University of Vienna (1971) the City University of New York (1972). On 2 June 1995 he received an honorary doctorate from the Faculty of Social Sciences at Uppsala University, Sweden. He was elected a Foreign Member of the Royal Society (ForMemRS) in 2006.

Arrow was one of the precursors of endogenous growth theory, which seeks to explain the source of technical change, which is a key driver of economic growth. Until this theory came to prominence, technical change was assumed to occur exogenously – that is, it was assumed to occur outside economic activities, and was outside (exogenous) to Common economic Models. At the same time there was no economic explanation for why it occurred. Endogenous-growth theory provided standard economic reasons for why firms innovate, leading economists to think of innovation and technical change as determined by economic actors, that is endogenously to economic activities, and thus belong inside the model. Endogenous growth theory started with Paul Romer's 1986 paper, borrowing from Arrow's 1962 "learning-by-doing" model which introduced a mechanism to eliminate diminishing returns in aggregate output. A literature on this theory has developed subsequently to Arrow's work.

Arrow died in his Palo Alto, California home on 21 February 2017 at the age of 95.