- 1973: Several leaders of WELS and ELS congregations in Washington, Ozaukee, and Dodge counties gather to discuss a proposed Lutheran high school in the northern Milwaukee metro area.
- 1974: KMLHS opens with an enrollment of 35 students in grades nine and ten at the temporary facility of Christ Lutheran Church in the village of Jackson.
- 1975: Forty-eight acres of land are purchased along Division Road in the town of Jackson for $36,500. A federation of congregations is organized.
- 1976: KML breaks ground for a 21,760 square foot building. The KML federation totals 14 congregations.
- 1977: KML moves into the new facility. First senior class of 15 students graduates.
- 1980: Student body grows to 230, groundbreaking for $800,000 gymnasium/classroom addition, first Echo Fest.
- 1989: Central IMC space renovated into library and media center.
- 1993: Groundbreaking for 11,000 square foot, $500,000 classroom addition.
- 1994: Dedication of the Project Grow addition (Business office, home ec. classroom, and science facilities expanded. Student body numbers 315.
- 1996: Computer Assisted Drafting and Design (CADD) purchased through Ladies Guild and Thrifty Nickel retail store.
- 1999: Computers on Wheels (COWS) funded by KML’s First Annual Auction through Friends/Founders. KML celebrates its 25th year. Student body numbers 390. Twenty-six congregations from five counties make up the KML Federation.
- 2001: Groundbreaking for Time to Grow expansion.
- 2003: Dedication of Phase I Time to Grow project takes place on October 5. Education wing, kitchen, cafeteria, new and remodeled gymnasiums, and locker rooms are part of the $5.5 million expansion. Outdoor athletic fields change the entire look of the KML campus.
- 2004: Dedication of the Green Machine wastewater treatment project.
- 2011: Soccer bleachers were added to the outdoor sports facilities.
- 2012: Groundbreaking for the Performing Arts Center and fine arts academic wing.
- 2015: Outdoor lights added to the football field which was renamed Catalyst Coliseum
- 2019: Groundbreaking for the $4.4 million Science & Innovation Wing takes place in February. Four science labs and classrooms on the second floor are completed by the beginning of the 2019-2020 school year in August.
- 2020: Transition in March to all classes held virtually as a result of Wisconsin’s governor closing schools for face-to-face learning due to COVID-19. Face to face instruction (five days per week) resumes in August at the beginning of the 2020-2021 school year.
- 2021: Seven classrooms on the first floor of the Science & Innovation Wing are finished, completing the building project begun in 2019.
