The 10-mile O&I was built by the Ensign-Oskamp Company in 1899-1901 as a logging railroad. It was determined by the Railroad Commission of Georgia to be a common carrier in 1901. In 1902 the line was extended west from Irwinville about 6 miles to the Alapaha River at Crystal Lake, but that new section apparently only operated as a logging road.
The railroad had one locomotive, one passenger car, and 46 freight cars. It was purchased by the Brunswick & Birmingham in March of 1903.
In 1907 the Fitzgerald, Ocilla, & Broxton Railroad was formed to take over part of the former Ocilla & Valdosta Railroad. Sometime afterwards, the O&I was leased to the FO&B.
In 1911 the FO&B leased the line, along with the tracks between Ocilla and Fitgerald, to the Ocilla Southern Railroad. The OS was in the process of assembling a railroad from Alapaha to Rochelle and needed an Ocilla-Fitzgerald link as part of its plan. The Ocilla-Irwinville line remained as a lightly used branch until it was abandoned in 1915-16.
Larry Goolsby. Atlanta, Birmingham & Coast. Published by the Atlantic Coast Line & Seaboard Air Line Railroads Historical Society, 2000.