Rathmore Grammar School is paired with the Nicolaus-Cusanus-Gymnasium in Bonn, Germany and Colegio de San Jose in Madrid, Spain.

Similarly in 2016, it was the top-performing school in Northern Ireland in terms of GCSE and A-Level results, thus placing 38th in the UK.

[4] In 2018 it was ranked 20th in Northern Ireland for its GCSE performance with 98.3% of its entrants receiving five or more GCSEs at grades A* to C, including the core subjects English and Maths.

In 2010, Rathmore 4th years won the Leopold Cup in hurling, defeating Belfast neighbors St. Malachy's in the final.

They have also tasted success in basketball with the under-16 boys winning the Northern Ireland Cup in 2012 and finishing 2nd place the previous year.