Despite officially opening as a high school in 2005, the building was built a year earlier and functioned as a temporary elementary school due to the nearby Lincoln Alexander Public School experiencing major construction setbacks. During the 2005/2006 school year, another York Region District School Board elementary school occupied the third floor due to an extensive asbestos cleanup occurring in their building. At this time, secondary school classes were restricted to the first and second floors.
Richmond Green had an enrollment of approximately 330 Grade 9 and 10 students and over 30 staff in its inaugural school year. Most of the Grade 10 students came from nearby Bayview Secondary School and Richmond Hill High School. In its second year, the number of students increased to 500 as Grade 11 courses were added. The 2007/2008 school year found the student population increased to 850 students, with Grade 12 being added. In May 2009, Richmond Green had approximately 1000 students, with new students arriving regularly due to new housing developments in Richmond Hill and Markham. As of January 2014, the population of the school is over 1200.