[1] Halliwell started his career in the youth team at London side Wimbledon, before moving in the Scottish Football League with Clyde.
After leaving the Cumbernauld side in 2005, Halliwell spent the next six years playing for seven different Scottish clubs, culminating in a loan spell back at Clyde from former rivals Partick Thistle.
Bryn's son, Alfie Halliwell, who is in the Rangers FC Academy, was selected for the Scotland under-16 squad in August 2022 He began his career at the now defunct Wimbledon, but it was at Clyde, whom he joined in 2000, where he established himself.
After a successful trial spell, Halliwell was signed by Queen of the South manager Gordon Chisholm minutes before their first pre-season game against Scottish Football League newcomers Annan Athletic on 12 July 2008.
[9] After a spell in the junior ranks with Gartcairn, Halliwell appeared for Forfar Athletic as a trialist on 11 March 2017 in a 2–1 defeat to Edinburgh City following a suspension to regular keeper Grant Adam.