Decatur High School (DHS) is a high school in Decatur, Georgia, United States. It is City Schools of Decatur's sole high school and was established in 1912 as a boy's high school.

The school became co-ed in 1953. The current building was built in 1965. The campus also hosts a "Performing Arts Center," opened in November 2009, which includes a theatre, basketball court, additional classrooms, a 4,000 seat stadium, rehearsal room, and a range of multi-use spaces. In 2018, the main building was renovated with the addition of a new media center, a cafeteria, a new lobby area, and additional classrooms.

The standard core curriculum at Decatur High School is taught at the college-preparatory level, advanced, and the Advanced Placement level may begin in the 10th grade. Students may also enroll in work-study opportunities or internships, and take joint enrollment classes at local colleges. 97% of the class of 2024 attended a four-year college and 81% met the HOPE Scholarship.

The average scores for the PSAT, the SAT, and the Georgia High School Graduation Test are all above the state averages with class of 2024 reporting an average ACT of 24.6 and an SAT of 1169. 170 students in the class of 2022 completed the ACT, while 75% of students in the class of 2023 completed the SAT. The school met Adequate Yearly Progress for the 2010–2011 school year. Students also have to take the MAP (Measures of Academic Progress) tests three times every year until their senior year.

The school continues the International Baccalaureate middle years programme started at Beacon Hill Middle School through the 9th and 10th grades. Sophomores may apply to the IB Diploma Programme or IB Career Programme after completion of the middle years program. The IB Career Programme courses which Decatur offers include: Architectural Drawing and Design, JROTC, Career & Technical Instruction, Certified Nursing Assistant Certification, Computer Science, Convergence Media/Audio-Visual Technology Film, Culinary Arts, Early Childhood Education, Furniture Design, Graphic Design, IB Design Technology, Teaching as a Profession, and Work-Based Learning. The Class of 2025 is estimated to graduate with 107 Full IB Diploma program and 50 IB Career program candidates, along with an additional 50 seniors sitting for IB exams. 100 students of the class of 2025 are reported to be participating in dual enrollment courses.

Athletic activities include Baseball, Basketball, Cross Country, E-Sports, Flag Football, Football, Golf, Gymnastics, Lacrosse, Literary, Soccer, Softball, Swimming, Tennis, Track, Volleyball, Water Polo, and Wrestling.

• Became an AP Honor School and was included in The Washington Post's Challenge Index.
• Five seniors entered the HerWorld competition and won by designing a smart toothbrush.

• The DHS Mock Trial Team won the Georgia mock trial state championship

• Decatur Mayor Patti Garrett presented the DHS Ivy League club a certificate of appreciation during a Decatur City Commission meeting for showing commitment to environmental conservation and for contributing to "the community’s natural beauty."

• CSD was ranked first out of 172 participating school districts for ACT scores, and second out of 182 schools for SAT scores in the state

• The Boys Cross Country Team won the Class 5A State Championship in 2019, the school's first State Title in Cross County

• On 14, May, 2022 the girls ultimate frisbee team won the state girls ultimate frisbee championship, ending their season undefeated.

• The DHS Boys and Girls Cross County both won the 5A GHSA State Championship respectively. Three runners were named to the Atlanta Track Club All-Metro Cross Country Team.

In May of 2020 a video began circulating showing a DHS student, and son of DHS IB coordinator and instructional coach Cheryl Nahamias, holding a toy gun, using racial slurs and threatening black DHS students. Cheryl Nahamias was demoted and reassigned to a job in CSD's central offices after defending her sons actions. In December of 2020 Cheryl Nahamias, who is white, filed a racial discrimination suit against City Schools of Decatur, stating through her attorney that "[I] believe the City Schools of Decatur has violated Dr. Nahmias' civil, constitutional, and educational privacy rights. We intend to prove that [Superintendent David] Dude and his administration have created a work environment that is hostile to legally protected speech and whistleblowers. ... We intend to hold CSD and its administrators accountable for this egregious conduct.". In January of 2022 it was reported that CSD settled with Cheryl Nahamias out of court and agreed to pay her three hundred and fifty thousand dollars.

At a football game played in late August 2022 against Flowery Branch High School Decatur High School students spat on members of the Flowery Branch High School band, pulled feathers from the hats of members of the FBHS band and sexually harassed the FBHS majorettes. Additionally students from DHS consumed alcohol and drugs, got into fights, and vandalized the stadium. These events resulted in DHS implementing a new suite of policies intended to curb student misconduct at sporting events; including banning students from standing on the benches, increasing supervision of the event by members of the school staff and disallowing students from bringing bags into stadiums.

• Roy Blount, Jr., writer and humorist
• Pete Case, former professional football player
• Felipe Claybrooks, former professional football player
• DeForest Kelley, actor
• Gorden Kelley, former professional football player
• Larry Morris, former professional football player, College Football Hall of Fame member
• Morgan Saylor, actress
• David Sims, former professional football player
• Jordan Walker, professional baseball player
• Herb White, former professional basketball player
• Daniel Wilcox, former professional football player

• Decatur High School