[2] Founded in 1392, it is amongst the oldest extant schools in England, with alumni including Nicholas Saunderson, the probable inventor of Bayes theorem, in the 18th century.

[3] At various times in its history it has been single-sex and mixed, free and fee-paying, selective and comprehensive, boarding and day.

in 1860, which first wrote their own Sheffield rules then merged them with Cambridge's to create the modern laws of the game in 1863.

[8] In 1886, the Charities Commission restructured the school, replacing the majority of its trustees with local government representation.

[11] Several other buildings were erected, and in 1974, PGS purchased the former Penistone Union Workhouse, later named 'Netherfields', which became the school's sixth form.

The school's traditional motto is "Disce Aut Discede" ("Learn or leave") but since 2010 it has used "Never Stop Flying", a reference to martlets having no feet so always being in flight.

In 2017, Penistone Grammar School introduced a controversial, zero tolerance style 'Values Driven Expectations' behaviour management scheme, under which a pupil could be reprimanded for forgetting a pen or leaving their shirt untucked.

[13] After internal remodelling in 2018, work started on a £4.3 million two-storey extension in 2019, providing an additional 250 places at the school.

The building was opened to students in September 2020, and is linked to the main school by a walkway through the science department.

The school maintains a 30 acre site in the west of Penistone, including extensive playing fields, used mostly for football, rugby, cricket, and athletics.

[19] Prefects remain members of their original house but join an additional group known as "Clarels" and wear red.