Students graduating from McMillen will attend Plano East Senior High School for the eleventh and twelfth grades.

McMillen has a total of 67 classrooms, 10 science laboratories, band and music spaces, library, competition and practice gymnasiums, an auditorium, and a full-service cafeteria and kitchen.

[5] Because McMillen was built in 2011, the campus features many unique design and architectural aspects that are not found at any other school in the district.

SHW Group designed the 278,800 SF building to include a series of both formal and informal learning spaces.

Each education wing is intended to promote collaboration between students and teachers in both the "pod" (an innovative learning and gathering area featuring whiteboards, study tables, and chairs) and the classrooms surrounding it.

He replaced Brian Lions, who is now the current head of Plano ISD's Director for Diversity, Equity & Inclusion.

Current assistant principals are Nick King, Kamden Kneisel, Mary Cabrera, and Kamili Carthlege.

In Spring 2016, McMillen instituted mandatory academic tutorials during the first half of "Lions Lunch" for students failing 2 or more classes.

In addition to the AP courses McMillen High School offers, the campus also has a range of On-Level and Pre-AP (Honors) courses for students to choose from, as well as various electives such as Advancement Via Individual Determination (AVID), Peer Assistance and Leadership (PALs), fine arts, art, engineering, and computer technology.

Their marching shows over the past years were Pirates of the Caribbean (2012), Arabian Nights (2013), Frozen (2014), Holst's The Planets (2015), New World Symphony (2016), Time (2017), and Blend (2018) The bands, orchestras, and choirs perform in University Interscholastic League (UIL) festivals, as well as local music contests, such as the Choice Music Events.

McMillen also hosts the Plano Independent School District East Cluster Solo & Ensemble Festival each spring for orchestra students.