Coddington grew up in Rupert, Idaho, reading all the car and hot rod magazines he could, and got his first car (a 1931 Chevrolet truck) at age 13. He attended machinist trade school and completed a three-year apprenticeship in machining. In 1968, he moved to California building hot rods by day and working as a machinist at Disneyland during the night. He soon became known for building unique hot rods and in 1977 he opened his own shop, Hot Rods by Boyd, in Cypress, California. His first major customer was Vern Luce whose car, a 1933 coupe, won the Al Slonaker Award at the 1981 Oakland Roadster show.
Coddington was known for clean, elegant designs combining old school with what would come to be known as the "Boyd Look".
Some of Coddington's signature innovations were his custom-fabricated alloy wheels, typically machined from a solid aluminum billet, an industry first. Together with John Buttera, Boyd pioneered this "billet" machined look and applied it not only to wheels, but broadly throughout the car.
In 1988, Coddington founded Boyd's Wheels, Inc., to manufacture and market his custom billet wheels.
In 1989, the "CadZZilla", a customized 1949 Cadillac, was commissioned by ZZ Top's Billy Gibbons, conceived by Jack Chisenhall and designed by Jack Chisenhall and Larry Erickson. It is acclaimed as one of the great expressions of automotive customization. Columnist Gray Baskerville called CadZZilla "the most incredible transformation he'd ever witnessed", and in their "History of Hot Rods & Customs" the auto editors of Consumer Guide praise it as "the first really new type of custom since the heyday of the 1950s".
Many of the next generation of customizers started their career with Coddington. Larry Erickson, later the chief designer of the Mustang and Thunderbird for Ford Motor Co., worked with Coddington early on, and specifically credits the CadZZilla collaboration for jump-starting his career. Designer Chip Foose (Overhaulin') and fabricator Jesse James (Motorcycle Mania). both started their careers in his shop. Coddington hosted the Discovery Channel show American Hot Rod.
Coddington's creations have won the Grand National Roadster Show's "America's Most Beautiful Roadster (AMBR)" award seven times (the only back-to-back winner of America's Most Beautiful Roadster) and the Daimler-Chrysler Design Excellence award twice, and earned him entry into the Grand National Roadster Show Hall of Fame, the SEMA Hall of Fame, the Route 66 Hall of Fame, and the National Rod & Custom Museum Hall of Fame. In 1997, Coddington was inducted into the Hot Rod Hall of Fame.
In 1998, financial trouble due to a $465,000 loss from a bankrupt customer led Coddington to re-organize Boyd's Wheels and partner with his eldest son (Boyd Coddington, Jr.).
In his later days, he began registering cars that were essentially completely custom fabrications as antique automobiles, avoiding major emissions restrictions and tax liabilities. California officials considered this a "ship of Theseus" fraud, claiming that so many central elements were replaced, the cars ceased to be the same entity. Coddington was charged with a misdemeanor and pleaded guilty on April 7, 2005.
Coddington was hospitalized on December 31, 2007. He was discharged shortly after New Year's Eve, but was readmitted a few days later to Presbyterian Intercommunity Hospital in Whittier, California. Doctors performed surgery; despite the prognosis of a complete recovery, Coddington died on February 27, 2008. His publicist stated that Coddington was a long-time diabetic who died from complications that were brought on from a recent surgery for a perforated colon along with sepsis and kidney complications.
Coddington was buried at Rose Hills Memorial Park in Whittier, California.