According to The Guardian, he had suffered from a long illness.
"It was expected, but it's sad nonetheless," Baker's niece Abigail Shield told the newspaper. "He had a very long and fulfilled life. He brought lots of happiness to people and we'll be celebrating the fact that he was well loved throughout the world. We're all very proud of what he achieved in his lifetime."
Standing 3 feet, 8 inches tall, Baker began performing at age 16, first in a theatrical troupe and then in a circus, ice shows and the musical comedy act The Mini Tones. Following a handful of minor film and television appearances, he landed his breakout role as R2-D2 in 1977's "Star Wars."
Baker returned to play the beloved droid in the "Star Wars Holiday Special," "The Empire Strikes Back," "Return of the Jedi," and the three prequels. He was credited as "R2 Consultant" on "The Force Awakens."
In 1978, as R2-D2, Baker embedded his footprints into concrete outside of the legendary Grauman's Chinese Theatre in Los Angeles.
His career extends beyond "Star Wars," however, with roles in such films as "Flash Gordon," "The Elephant Man," "Time Bandits," "Labyrinth" and "Willow."
Note: Early reports misstated Kenny Baker's age. He was 81.