Sutton served in the Navy during World War II before becoming involved in auto racing. His introduction to the sport was inauspicious — he spun out in the first corner on his very first lap at a dirt track — but he persevered. He won Oregon Racing Association championships in 1949, 1950, 1954, and 1955, establishing himself as one of the Pacific Northwest's top oval racers. He also captured midget car racing championships in Portland.
During the 1954 Carrera Panamericana road race, Sutton flipped his car to avoid cattle on the course and spent the following four months in a body cast — an early indication of the physical toll his career would extract.
Sutton raced in the AAA and USAC Championship Car series from 1955 to 1965, making 76 starts and recording 43 top-ten finishes and three victories. He completed his Indianapolis 500 rookie test in 1956 and made his first start in the race in 1958, finishing 32nd after being caught in a multi-car accident on the opening lap.
The 1957 attempt at Indianapolis was especially dangerous: Sutton flipped while attempting 140 miles per hour and slid upside down with his helmet scraping the asphalt for nearly 1,000 feet. The Indianapolis News reported the following morning that he was initially believed dead by trackside observers. He sustained a fractured skull, broken shoulder, and serious abrasions, yet returned to racing.
His finest hour at Indianapolis came in 1962. Starting from fourth on the grid, Sutton led nine laps during the race and ultimately finished second behind his teammate Rodger Ward. The result placed him among the top finishers in one of the most competitive eras in the event's history. The following year, during a tire test at Indianapolis Motor Speedway, Sutton posted an unofficial track record by exceeding 155 miles per hour.
Sutton was known throughout his career for versatility, competing across roadsters, midgets, sprint cars, and stock cars. He entered the 1963 Daytona 500 and finished 31st, one of several stock car appearances that demonstrated his comfort with multiple disciplines.
He retired from driving in 1965 during a race at Langhorne Speedway after watching his fellow competitor Mel Kenyon suffer severe burns in the same event. The moment crystallized a decision he had been approaching, and he stepped away from the cockpit.
After retiring as a driver, Sutton transitioned into broadcasting and became a member of the Indianapolis Motor Speedway Radio Network for many years, bringing his on-track knowledge to radio coverage of the race that had defined his career.
Sutton was inducted into the West Coast Stock Car Hall of Fame in 2005 and was a member of the Oregon Sports Hall of Fame. He was named to the National Midget Auto Racing Hall of Fame in 2009, three years after his death.
Len Sutton died on December 3, 2006, at his home in Portland at the age of 81, following a long battle with cancer.