Gun Hägglund started her career at Swedish Radio in 1955 where she worked at the foreign news desk as a secretary and program announcer.

In an interview from 1966, Hägglund describes the rather complicated process of translating textual versions of the dialog in films and television programs into short subtitles of text at the bottom of the screen.

[8] For the general public, Hägglund is probably best known for her participation in Swedish television's entertainment programs and daily shows such as Halvsju (Half Past Six O'Clock), Razzel, Träna med TV (Workout with TV), and Café Sundsvall.

Hägglund was married to news editor Karl-Axel Sjöblom (known as KAS) with whom she co-hosted Halvsju, one of the most popular television shows in Swedish history.

[9] For 30 years, until 1997, Hägglund was closely involved in the Svenska Cykelfrämjandet (National Association for Promotion of Cycling), first as Secretary-General, and later Executive Chairman.