Spinney was born in Waltham, Massachusetts and graduated from Acton High School. When he was in the US Air Force, he wrote and illustrated Harvey, a comic strip about military life. He also animated a series of black and white cartoons called Crazy Crayon. These were done under the pseudonym "Ed Spinney."
In 1955, Spinney headed to Las Vegas, Nevada, where he created the show Rascal Rabbit. He returned to Boston, joining The Judy and Goggle Show in 1958 as a puppeteer. At this series, he was Goggle, to Judy Valentine's Judy.
Throughout the 1960s, he performed on the Boston broadcast of Bozo's Big Top, where he played Mr. Lion, who created cartoons from the names of children participating in the show. Through that decade, he was also a commercial artist and animator.
Spinney created a puppet of a cat named Picklepuss, long before he joined the inaugural cast of Sesame Street. This cat and his other friends joined Spinney in entertaining audiences of the 1960s. Spinney's Picklepuss and Pop puppets were characters in the 1988 family video Wow, You're a Cartoonist!, starring Tatyana Ali.
Spinney currently resides in Woodstock, Connecticut, with his wife, Debra. The couple have three children.
As Oscar the Grouch he has written How to Be a Grouch, a Whitman Tell-A-Tale picture book. With J Milligan, he wrote the 2003 book The Wisdom of Big Bird (and the Dark Genius of Oscar the Grouch): Lessons from a Life in Feathers (ISBN 0-375-50781-7).
His work has been studied by other international puppeteers, who structure their performance styles after his, most evidently with full-body puppet costumes. The Chinese performer of Da Niao on Zhima Jie is most evident of this, as the character is an exact physical replica of Big Bird.
Over the past 36 years, Spinney has been honored with four Daytime Emmy Awards, for his portrayals on the series, and two Grammy Awards for his related recordings. Two of the recordings Spinney performs on have earned Gold Record status. For his body of work, Spinney has received both a star on the Hollywood Walk of Fame in 1994 and the Library of Congress's Living Legend award in 2000.
Over his career as Big Bird/Oscar, Spinney has:
At the 2006 Daytime Emmy Awards, Spinney received the National Academy of Television Arts and Sciences' Lifetime Achievement Award. "I am elated and amazed to receive this honor from those who are committed to the best of what television and media have to offer, for doing what I've always wanted to do."
Spinney was the puppeteer of Baby Monster in the early 1970s. Baby was taken over by another puppeteer, becoming Elmo.