Clendon Mason Memorial Secondary School has a long and rich history of success in both academia and sports at the district and 
national levels. The latest achievements have been listed below:
Academics
- 2020 (January) – Tonia Harlow, Merlaner Joseph and Sean St.Rose emerged as overall winners of the Annual Zone 3 Science Quiz Competition.
- 2018 (March) – CMMSS Students won the top three prizes in the French Poetry Competition organised for Franconie Day 2018. Concours de poesie – 2018
PREMIÈRE PLACE: Edith Gia Bernard
DEUXIÈME PLACE: Runnifer Joesph
TROISIÈME PLACE: Vernege Noellien - 2017 (June) – Shequanda Wilfred of 3-1 won the Collins Spelling Bee placing 1st among eight other secondary schools. She represented C.M.M.S.S and District 5.
- 2014 – Upper Secondary National Agricultural Science Quiz – 1st Place
- 2014 – Ministry and Education Secondary Schools Website Competition – 2nd place
- 2014 – Lower Secondary National Secondary Science & Technology Quiz (Zone III) – 2nd place
- 2013 – National Science & Technology Fair District 5 – 1st Place
Sports
- 2016 – National Under 19 Inter Secondary Schools Football finalists (won every game except final vs Sir Arthur Lewis Community College)
- 2013-2014 – National Under 19 Inter Secondary Schools Football champions
- 2014 – National Inter Secondary Schools Cricket-rama champions
- 2013 – National Males Inter Secondary Schools Volleyball Competition finalist
- 2013 – National Females Inter Secondary Schools Volleyball Competition 3rd place
- Representation on various National junior and schools basketball, cricket, football, netball and volleyball teams
- Saint Lucia National Cricket Female Junior Cricketer of the Year (Ms Paulina Francis)