This spacious and dignified hall is used for all school functions, lectures, theatricals, debates and cinema shows. The walls are adorned with numerous honours boards and portraits of past Headmasters for over one hundred thirty years. The stage is equipped with mechanical and electrical apparatus, and there is a pit for the orchestra. The Amateur Dramatic Society has a reputation as high as that of the choir. The portrait of the founder Bishop Cotton was painted by Mr. Eddis in 1852 which hangs in the Arnold Library at Rugby. Mr. Eddis consented to accept the subscription raised by the boys amounting to
Rs.720/- to paint a modified copy of this former portrait. It was unveiled in 1869 and adorns the walls of Irwin Hall.

The Irwin Hall is named after HE Rt. Hon. E F L Wood, GMSI, GMIE, Baron Irwin of Kirby and Enderdale in the County of York, Viceroy and Governor General of India, who inaugurated the Hall on 20th September 1930.

During the tumultuous partition days, on 22nd October 1947, the Headmaster addressed 42 Pakistani Muslim boys in the Irwin hall in the presence of the School and the Staff. After his address, the middle door of the hall, through which, according to an old tradition, only Viceroys and Presidents enter and school Captains leave the school, was flung open by two prefects and Hasan Agha, the School Captain walked out, not among the cheers of his fellow students, as previous School Captains had done, but in deep and sorrowful silence.