Cobb County was one of 10 northwest Georgia counties carved out of Cherokee Indian lands in 1832. Named in honor of former U.S. Senator, Representative and Superior Court Judge Thomas Willis Cobb of Greensboro, the land was first home to Native American settlements including Sweet Water Town on Sweetwater Creek (southwest of Marietta), Big Shanty (later Kennesaw) on Noonday Creek (five miles north of Marietta) and Buffalo Fish (southeast of Marietta).

Marietta, settled in 1833 and designated the county seat in 1834, developed in the geographical center of the new county. Marietta received its official charter in 1852.

Located in the upper Piedmont region, Cobb County had few large plantations, developing instead around small subsistence farms. Towns and settlements grew after the U. S. Army removed the Cherokees to western lands in 1838. By 1850, Marietta was a popular resort community with several hotels attracting summer visitors seeking a cooler, healthier climate than the Georgia and South Carolina coast.

Other towns established in the 1830s were Springville (later Powder Springs, 1838) and Roswell (1839). (The thriving industrial center of Roswell was part of Cobb County until 1932.)

Acworth became a community in the early 1840s and received its city charter in 1860.

Big Shanty, which got its name from the shanty town for railroad construction workers in the late 1830s, received its town charter as Kennesaw in 1887.

Smyrna Camp Ground, which later shortened its name to Smyrna, was a well known religious encampment in the early 1830s and an early railroad stop in the 1840s. Smyrna was incorporated in 1872.

Austell was settled in the late 1800s and chartered in 1885.

During the Civil War (1861-1865), General William T. Sherman led an invading Union army from Chattanooga, Tennessee, toward Atlanta as part of the Atlanta Campaign. Several bloody battles were fought in Cobb in June and July 1864, including the Battle of Kennesaw Mountain.

Cobb County held its 175th Anniversary Monday, Dec. 3, 2007 at the new Cobb Energy Performing Arts Centre. The event pre-show began with the third place Bands of America Grand National Champion Kennesaw Mountain High School marching band playing in the plaza and small ensembles of the Georgia Youth Symphony Orchestra performing on each level of the lobby. Artwork created by local artists and students was on display as well.

The high-energy anniversary celebration performance included a production number from the Pebblebrook High School Center for Excellence in Performing Arts touring ensemble, performances by a 250 voice honor chorus from metro area elementary schools and dance numbers by the Georgia Ballet, Dance Stop Studio and the Ruth Mitchell Dance Company. The second half of the performance featured the Cobb Symphony Orchestra, Theatre in the Square and a video montage of the history of Cobb, performances by Miss Cobb County and a few surprises.

Looking East to strengthen cultural, business and education ties

City of Seongdong-Gu

In October of 2012 a delegation of community, business and education leaders spent six days in Seongdong-Gu, South Korea.

Members of the delegation included Cobb Chamber of Commerce Chairman Tony Britton; Walton High School principal Judy McNeill; Marietta City Schools Superintendent Dr. Emily Lembeck; county economic development director Michael Hughes; Sunny Park, president of the America Korea Friendship Society; Dr. Robin Dorff, dean of the Kennesaw State University College of Humanities and Social Sciences; and Dr. Carolyn Dorff, a music instructor at KSU.

Cobb County signed an agreement with the South Korean district's Chamber of Commerce to make it an official extension of the Cobb Chamber. They facilitated communications with businesses looking to expand to the United State, specifically to Georgia. The delegation also met with members of local schools and the convention and visitors bureau.

Since establishing the partnership, many Cobb County high school and college students have visited their sister and peer organizations in South Korea as part of an enrichment and cultural exchange program. For the last few years, students from the Seongdong-Gu School District and Hanyang University have reciprocated by visiting and studying in Cobb.

Cobb County and Seongdong-Gu, a district in Seoul, have had a sister-city relationship since 2007. Seongdong-Gu is one of the 25 "gu",or districts, which make up the city of Seoul, South Korea. It is situated on the north bank of the Han River and is divided into 20 neighborhoods. The city's tagline is "Seongdong-Gu: Where dreams become reality."