He founded Ingalls Iron Works in Titusville, Birmingham, Alabama in 1910. He also established Ingalls Shipbuilding in 1938. They became the largest privately owned steel manufacturer in the Southern United States and the largest shipyard in the Gulf Coast of the United States.
In 1937, he started a shipyard in Decatur, Alabama.
To accommodate the growing needs of the Second World War, it was moved to Birmingham, Alabama, then to Chickasaw, Alabama, and finally in Pascagoula, Mississippi. By the time of his death, his company was worth United States$40 million.
He established the Ingalls Foundation in 1943. He died in 1951. He sold Ingalls Industries to Litton Industries in 1961, which was ultimately purchased by Northrop Grumman in 2001.
He was also a yachtsman, who owned the yacht Rhonda III.
The Robert I. Ingalls, Senior
Hall on the campus of Samford University in Homewood, Alabama is named in his honor. lieutenant was built in 1957, and it is home to the McWhorter School of Pharmacy.