One of the country's most prolific stage and film actors, he is probably most widely recognised for his two heterogeneous roles in the Martin Beck universe; as the eponymous killer in Bo Widerberg's The Man on the Roof in 1976,[2] and the recurrent role as "The Neighbor" in the mass produced film series, a rambunctious raconteur who frequently interacts with the titular police investigator for the purpose of comic relief.

[3] He also had a role in the film adaptation of Stieg Larsson's Millennium series as the lawyer Dirch Frode, and starred as various colourful characters in Lars Molin's comedies.

[5] Since the early 1960s he has been active as an actor in many films and TV series and on theatrical stages, mainly the Stockholm City Theatre.

His most well-recognised role in his closing decades was as the eccentric “The Neighbor”, a rambunctious raconteur living next to the eponymous homicide investigator Martin Beck and often providing comic relief, and occasionally (unintentionally) vital insights, in the many Martin Beck TV movies made from 1997 into the 2020s.

In December 1993, Hirdwall played the leading role in the Swedish TV company SVT's annual children's Christmas "Advent calendar" – Tomtemaskinen (The mechanical Santa), one of the Pettson and Findus stories by Sven Nordqvist – with one 15-minute part shown each day until Christmas Eve.