Roy Britten was born in Washington D.C. His mother worked at the National Research Council and his father was a statistician. Britten was exposed to science early on. Growing up, Britten and his brother shared a basement chemistry lab. He also frequented the public exhibits in the rotunda of one of the National Academy buildings, where he could see the working of a Foucault pendulum and learn about sunspots.

In 1940, he went to the University of Virginia to study physics. Not long after, he was recruited to work on the Manhattan Project. He didn't return to school until 1946. He went to Princeton to do graduate work in nuclear physics.

By the time he finished his Ph.D. in 1951, Britten had decided that the world of nuclear physics had changed. He made plans to do post-doctoral work in biophysics at the Department of Terrestrial Magnetism in the Carnegie Institution in Washington. He took the phage course at Cold Spring Harbor Laboratory to brush up on his biology, and started working on the kinetics of DNA hybridization with the group at the Carnegie. Through this work, Britten showed that eukaryotic genomes have many repetitive, non-coding DNA sequences.

Since his work on repetitive DNA, Britten has been interested in evolutionary biology, specifically the nature of repetitive DNA and its origin and evolutionary history. He has done work on human repetitive DNA elements like Alu, and repetitive DNA elements in sea urchins - a candidate organism for the sequencing project. He is also looking at other repetitive elements in the human genome from data generated by the Human Genome Sequencing Project.

Britten has been at the California Institute of Technology since 1970. He is part of the gene regulation research group and is a Distinguished Carnegie Senior Research Associate, Emeritus. He is also an adjunct professor at the University of California, Irvine.

Britten has a number of hobbies and interests outside of science. He has been a long-time sailor and musician; he plays the flute though admits that lately he hasn't had the time. Britten paints "oils, because water-color is too difficult." And to keep up with the times, he has been generating computer art. He writes science fiction. His artwork and fiction are currently still private.