In the late fall of 1928, Our Gang producer Hal Roach and director Robert F. McGowan began to look for an overweight child actor to replace Joe Cobb in the series. Joe was twelve years of age, and the Our Gang series was about to transition to sound. Roach and McGowan held a nationwide contest to find a replacement for Cobb. Chaney won this contest in early 1929, and was offered a two year contract.
Chaney was actually two years older than Joe Cobb, but was only four feet tall and about 113 pounds. Chaney, nicknamed "Chubby" in the series, made his debut in the second talking Our Gang comedy, Railroadin'. He appeared in two years' worth of Our Gang films, including shorts such as Boxing Gloves (1929, in which Chubby and Joe have a boxing match) and Teacher's Pet (1930).
By the spring of 1931, Chaney was visibly aging, getting taller and increasingly heavier. He finished out the 1930-31 season without being offered another contract. Both Chaney and his parents decided he would not pursue acting following his final Our Gang short, Fly My Kite (1931). Jackie Cooper, who had been in the series for about as long as Chaney, also departed Our Gang in early 1931, as did Mary Ann Jackson, a holdover from the silent Our Gangs, and stalwart Our Gang kid Allen "Farina" Hoskins, a member of the original 1922 cast.
After leaving the gang, Chaney returned to Maryland and entered public school, where he excelled in his studies. Chaney never grew beyond four feet and seven inches; his weight continued to increase, and it was discovered that he had a glandular ailment. He underwent surgery for his ailment in 1935, his weight dropping from over 300 pounds (136 kg) to less than 140 pounds (64 kg). Chaney became seriously ill afterwards, and died on May 29, 1936 at the age of 21, the death certificate indicating myocarditis as the cause. Chaney was the first of the regular Our Gang alumni to pass away, and the only one to not live to see the end of the series in 1944.