The Katy Independent School District (KISD) is a public school district based in Katy, Texas, United States, with an enrollment of over 85,700 students. In 2022, the district was given a grade of "A" by the Texas Education Agency.

The district serves 181 square miles (469 km²) in parts of Harris County, Fort Bend County and Waller County. Most of the district lies within the boundaries of the City of Houston, the City of Katy or their municipalities' extraterritorial jurisdiction (ETJ). Unincorporated areas in Katy ISD include Barker, Cinco Ranch, and Cimarron.

All residential areas of the district are assigned to an elementary school, a junior high school, and a high school by subdivision.

In 1898, the Katy Common School District (Katy CSD) was formed and the city built a 32 square foot, one-room school for all grade levels on 6th Street (now called George Bush Drive), where Katy Elementary is today. Winds from the catastrophic 1900 Galveston hurricane blew across the open prairie as far as Katy and destroyed the school building. The city rebuilt the school, and several other schools were built in quick succession in all three of Katy's counties.

In 1909 a new Katy CSD building was built next to the original one-room school on 6th Street. This was called Katy School, and it was a two-story building with a bell tower to call the students to class each morning. High school students attended classes in the new building, while elementary students continued to study in the smaller one. The bell is now above the entrance of Katy Elementary.

In 1918–1919, Katy's residents voted to separate the school from municipal control (called "divorcement") and to consolidate Katy CSD and other nearby schools within Katy's three counties into an independent school district (that is, a special-purpose district that is independent from local government control).

In March 2020, classes, campus events, field trips, student trips and competitions were postponed as a result of the COVID-19 pandemic in Texas. Virtual learning was put in place using Canvas, and was extended throughout the 2020–2021 school year during which two options were offered for returning students. The first involved in-person instruction, combining face-to-face teaching with digital learning through Canvas, including daily attendance tracking. The second option, the Katy Virtual Academy (KVA), offered real-time, live instruction via Canvas, allowing students to follow the KISD curriculum and meet Texas graduation requirements. Both in-person and virtual students adhered to the same grading guidelines, but the attendance requirement for the fall 2020 final exam eligibility was waived, allowing high school students to exempt a final exam if they met semester average and behavior requirements.

In adherence to safety measures, facial coverings were mandated for all district staff and students in grades 4 through 12, while students in pre-k through grade 3 were encouraged to wear face coverings. The protocol also included instructional day temperature checks for new district enrollees and late arrival students.