Cedarville Township was established in 1850 from land given by Xenia, Miami, and Ross townships.
It is the only Cedarville Township statewide. The township trustees meet in the Cedarville Opera House in Cedarville, which serves as the township hall.
Cedarville Township was originally settled by John and Thomas Townsley who migrated from nearby Kentucky . Prior to this, the area was inhabited by the native Hopewell and Adena tribes (the Adena’s were renown as "mound" builders). In 1801 the Townsley’s located on 1,000 acres of land along Massie Creek. The land was purchased for between $1.75 and $7.00 per acre. The village settlement was originally called Newport's Mill, then Hanna's Store, then the Burgh. The first official name was Milford, however, because of confusion with another Milford (near Cincinnati), the village at last adopted the name Cedarville to reflect its then-abundance of cedar trees.
The first school was built along Massie Creek in 1823 by a Mrs. Gamble, who was also the teacher. In 1829, the first church was built and, in 1834, the first post office began service. Massie Creek, which runs through the center of the village, was named for frontiersman General Nathanael Massie. Using this water power, three grist mills operated in the township. To transport the miller's products and livestock, a branch of the Little Miami Railroad passed through the center of the village. It is notable that Cedarville is centrally located to Cincinnati and Columbus, making it a strategic stopping point for travelers. Today, the remains of the railroad exist in the Ohio to Erie portion of the Little Miami Bike Path.
Whitelaw Reid, author of "Ohio in the War" (a compendium of events, reminisences, and Ohio regiment rosters of the Civil War) resided in Cedarville at the current home of U.S. Senator Mike DeWine. Mr. Reid began his journalism career at the Xenia Gazette and later succeeded Horace Greely as the editor of the New York Herald Tribune. In later years, Mr. Reid served as ambassador to England and France.
In 1850, Cedarville Township had a population of 2,716. Settlers continued to arrive in the area from Kentucky and South Carolina due to their opposition to slavery. During the Civil War, Greene County provided the largest number of Union troops in the state of Ohio, these primarily mustering with the 12th, 44th, 74th, 94th, and 185th infantry regiments, the 8th Cavalry, and the Ohio 10th Battery. Cedarville Township patriotically contributed 309 of its sons to the Union cause, one of the largest numbers in the region. Following the war, in 1866 a school built on Xenia Avenue was named the Union School. Average school attendance was 133.
The Cedarville Opera House, center of community life in the late 19th century, was originally constructed in 1886, only to be destroyed by fire within the year. Whitelaw Reid brought the architectural plans for the subsequent structure which was finished in 1888. It is a 1/3 scale replication of the Royal Albert Hall in London, England. John W. McLean of Cedarville was the builder of the new opera house. It is still standing today and in full use after nearly thirty years of neglect. In 1984 the Cedarville Opera House was placed on the National Register of Historic Places. Each year, a full array of programs including music, theater, and literary recitals are held for the enjoyment of the public.
The Reformed Presbyterians, in 1887, founded and incorporated Cedarville College, its objectives at that time to provide training for preachers and missionaries "For the Crown and the Covenant". It began official operation in 1892 in the building now known as "Founder's Hall". Eventually, management and full ownership of the institution was transferred to the Baptist Bible Institute of Cleveland (Ohio) when, in 1953, the campus perfectly filled BBI's growth needs. Today, Cedarville College is known as Cedarville University, a conservative Christian liberal arts university of arts, sciences, and professional programs. It serves over 2,850 students, 70% of whom are from out-of-state.