Following the arrival of the initial German settlers, they formally request the Los Angeles County superintendent to set up a school in Anaheim, their newly adopted town near the Santa Ana River.

[dubious – discuss] He left Anaheim to become the superintendent of the Los Angeles High School District in 1881.

In 1910 more space was needed and voters approved a bond in 1911 for $105,000 to buy eleven acres of land at the north east corner of Center Street (Lincoln Ave) and Citron just a half block away.

The school was the pride of the community for twenty-two years until the 1933 Long Beach earthquake occurred and rendered them unsafe.

Wimpy's Stand (selling burgers) was a popular landmark for several decades and was changed into the Student Activities Office in 1977.

Beginning in 1954, Anaheim Union High School went to a three-grade format with sophomores, juniors, and seniors in attendance.

Following the closure of Fremont Junior High School in 1979 and declining district-wide enrollments, AHS reverted to having a freshman class and a four-year student schedule beginning in 1980.

[4] The Clayes Field bleachers, which had been originally constructed in 1922 and was the only building on the campus that had survived the earthquake in 1933, was condemned in the early 2000s and was demolished in 2017.

The 1956 Anaheim football team was CIF co-champions with Downey, playing to a 13–13 tie at the Los Angeles Memorial Coliseum.