Located in Harmony, Seneca Valley High School is where everything—and everyone—in the district comes together. Comprised of approximately 1,200 juniors and seniors, the high school encompasses Cranberry Township, Jackson Township, Seven Fields, Evans City, Harmony, Zelienople, Callery, Forward Township and Lancaster Township. 

One of three schools on the Harmony campus (which also includes the Seneca Valley Middle School and the intermediate high school) the senior school boasts more than 60 sports, including baseball, football, soccer, basketball, track and swimming. Art Club, SADD, Ski Club and student council are just a few of the clubs offered at the high school level.

With Seneca Valley's district-wide technology system, students are provided with a variety of online opportunities, including cyber service education for those in grades 7–12 during the school day and at home.

In keeping with the Seneca Valley School District mission statement, to "provide an academically rigorous learning experience in a progressive environment, emphasizing civic responsibility and global awareness," the Senior High School requires senior students to complete a senior project in order to qualify for graduation. The area of study is the student's choice, but it must be community, career or enrichment related. The project consists of four parts: a research paper, a related project, a portfolio and an oral presentation.   

The principal of the school is Mark Korcinsky. The assistant principals are Jodi Perry and Jeffry Roberts. The cyber school assistant principal for secondary schools is Denise Manganello and the dean of students is Robert Ceh.