[citation needed] He worked for the Guardian Royal Exchange insurance company from 1956 until 1970; his broadcasting career started in 1965 on the pirate radio station Radio Scotland 242, which was closed down in 1967 under the provisions of the Marine Broadcasting Offences Act 1967.
Following the launch of BBC Radio Scotland in 1978, Mack returned to Scotland in 1979, becoming presenter of the mid-morning programme (The Jimmy Mack Show), which in 1988 broadcast live from the Glasgow Garden Festival for a total of 108 consecutive outside broadcasts, a possible record for such a programme.
In 1990, he left Radio Scotland to work for the commercial station Radio Clyde in the west of Scotland, becoming one of the station's main presenters on Clyde 2 from the launch on 3 January 1990.
Mack presented the drivetime show for eight years and also presented the weekday breakfast show on occasions when main presenter Dave Marshall was off in the early 1990s, in addition to this, Mack presented some weekend specialist shows on Clyde 2 for most of the 1990s - Clyde Gold, Relax with Mack, Jimmy Mack's Chart Countdown and a 1960s show before taking over the early evening and weekend breakfast shows from September 1997 until July 2000, In 2001, he launched his own Saturday night show called Saturday Night with Jimmy Mack.
He continued to broadcast on Radio Clyde until two weeks before his death from cancer on 3 July 2004.