During the 1992–93 school year, West Windsor-Plainsboro High School was awarded the National Blue Ribbon School Award of Excellence by the United States Department of Education, the highest award an American school can receive.
In its 2013 report on "America's Best High Schools", The Daily Beast ranked the school 129th in the nation among participating public high schools and 8th overall (and second for non-magnet schools) among schools in New Jersey. In 2012, US News ranked the school 11th in the nation for STEM (Science, Technology, Engineering, and Math). The school was ranked 132nd in the nation and seventh in New Jersey on the list of "America's Best High Schools 2012" prepared by The Daily Beast / Newsweek, with rankings based primarily on graduation rate, matriculation rate for college and number of Advanced Placement / International Baccalaureate courses taken per student, with lesser factors based on average scores on the SAT / ACT, average AP/IB scores and the number of AP/IB courses available to students. In August 2011, The Star-Ledger's Inside Jersey ranked the school 1st among the 330 public schools in the state of New Jersey. One notable feature of High School South is that it combines both AP Physics B and C courses into a single course known as Advanced Topics in Physics Honors. This required special permission from the College Board; this was approved when AP Courses were first made. It is the only school that offers such a course.
In the 2011 "Ranking America's High Schools" issue by The Washington Post, the school was ranked 9th in New Jersey and 407th nationwide.
The school was the 35th-ranked public high school in New Jersey out of 339 schools statewide in New Jersey Monthly magazine's September 2014 cover story on the state's "Top Public High Schools", using a new ranking methodology. The school had been ranked 62nd in the state of 328 schools in 2012, after being ranked 16th in 2010 out of 322 schools listed. The magazine ranked the school 21st in 2008 out of 316 schools. The school was ranked 9th in the magazine's September 2006 issue, which included 316 schools across the state. The school was ranked 5th in the 2004 issue, while West Windsor-Plainsboro High School North was ranked 1st during the same year.
Schooldigger.com ranked the school tied for 53rd out of 381 public high schools statewide in its 2011 rankings (a decrease of 29 positions from the 2010 ranking) which were based on the combined percentage of students classified as proficient or above proficient on the mathematics (93.1%) and language arts literacy (96.5%) components of the High School Proficiency Assessment (HSPA).