In 1941, Walker was forced to delay his Disney career to serve in the United States Navy during World War II.

Two years after Walt Disney's death in 1966, Walker became executive vice president and chief operating officer.

When Walt's brother Roy O. Disney died in 1971, Walker became company president, serving under chairman and CEO Donn Tatum.

In November 1976 Walker took over chief executive officer duties from Tatum while retaining the responsibilities of president.

Walker himself retired as CEO three years later, in February 1983, but stayed on as chairman until August 1984 to oversee the opening of Tokyo Disneyland in Japan.