Originally founded by the Religious of the Sacred Heart of Mary (RHSM), the university awarded associate, bachelor's, and graduate degrees.

In 1960, a new campus was started on Palos Verdes Peninsula that included dormitories for on-campus residential living, an auditorium, dining facility, a library, and a chapel.

In summer 2011, Marymount opened its Waterfront Campus in downtown San Pedro, Los Angeles.

In fall 2013, Marymount opened its Lakeside Campus in the community of Lucerne in rural Lake County, California.

[6] In March 2016 the WASC Senior College and University Commission questioned the viability of a Northern California campus and it closed in 2017.

[10][11] The Rancho Palos Verdes campus and the residential site in San Pedro were purchased by the University of California, Los Angeles.

[12] The Oceanview Campus encompasses 26 acres (11 ha) overlooking the Pacific Ocean and Catalina Island in Rancho Palos Verdes.

The university was a member of the National Association of Intercollegiate Athletics (NAIA), primarily competing in the California Pacific Conference (CalPac) from 2012–13 to 2021–22.