Architect James Riely Gordon designed Ellis County's present courthouse. Although he is listed on the cornerstone, Gordon was never employed as architect or provided professional services to Ellis County. Otto Kroeger, a San Antonio contractor and business relation of Gordon, sold Gordon's plans to the Ellis County Commissioners and was the initial contractor for the building. Due to the controversy between the Commissioners, the newly elected officials hired Fort Worth architect Marshal Sanguinet as consultant and construction supervisor, replacing Kroeger of his duties. Sanguinet is responsible for making cost saving changes to the original plans, freeing funds to employ the stone yard of Theodore Beilharz and his talented German stone carvers. The result is some of the finest stone work in the state of Texas. Credit must be given Beilharz and Sanguinet for the overall architectural success of the Ellis County Courthouse.

The contract price for the building was $150,000, the actual cost including furnishings was $175,000. The architectural style of the building is "Richardsonian Romanesque", named for architect H.H. Richardson whom Gordon's style emulates.

Ellis County Courthouse stands nine stories tall and contains 23,739 square feet. There are 12 inch steel beams supporting the courthouse running from street to street, north to south and east to west. The structure still retains its original copper gutters and down spouts. Inside, the walls are plaster on brick and are 20 inches thick. The floors are 8 inches thick and the ceilings are 9½ feet tall. During the courthouse construction, 50 to 70 men were employed at an average monthly payroll of $5000.

The building's primary foundation is concrete three feet thick, reinforced by twisted steel. Foundation walls up to the grade line contain about two million brick. On top of the brick, the building exterior consists mainly of 160 carloads of Burnett County red granite. The arches, trim and carvings are made up of 100 carloads of Pecos red sandstone. Fourteen carloads of iron are also contained in the structure. Ten thousand slate and ceramic tiles cover the roof. There has been much confusion concerning the location of the rock quarry supplying the red sandstone. Although it is called "Pecos" sandstone, the quarry (Quito Rock Quarry) was in Ward County five miles east of Barstow. The name "Pecos" is due to the proximity of the quarry to the town of Pecos, the county of Pecos and the Pecos river in west Texas. This quarry also supplied red sandstone for the construction of courthouses in Barstow, Dallas and San Antonio as well as the post office in Fort Worth.

Ellis County is one of about 40 Texas courthouses with a genuine clock tower. Nineteen of these were built in the 1890's. The four faced clock by E. Howard and Co. had a windup weight of 250 pounds, a bell striking weight of 800 pounds and a connecting steel cable 212 feet long. Like others of its kind, the clock is now powered by electricity.

The courthouse was originally built to house two courtrooms, the District Court on the second floor and the County Court (now the County Court at Law) located directly below on the first floor. The original judicial benches with their intricate woodwork are still found in these courtrooms. Part of the carving behind the bench of the District Court is blocked by the current ceiling. The District Courtroom, which was built to double as an auditorium, originally had a balcony area which was converted into office space for the third floor.

The original furnishings were designed by Gordon with Sanguinet and Messer of Fort Worth. Some of these still remain in the various woodwork, tables, chairs and cabinets. Also on the first floor remains a bullet hole in the door on the Commissioners Court Coordinator's office, which was formerly the sheriff's office. The hole was put there during a gun fight in the 1920's which left a deputy wounded and one man dead.