He began his career with the BBC in the north of England, where he commentated on rugby league for the North of England Home Service in the 1950s and 1960s. These broadcasts are largely unrecorded on the BBC Genome Project as it mainly uses the London edition of Radio Times and only has skeleton listings for the other regional Home Services. Genome does list an array of BBC work including contributions to Woman's Hour when it was broadcast from the north, much presentation work on religious programmes including Songs of Praise and Sunday Half Hour, and a stint as presenter of Rugby Special (usually covering rugby union), national coverage of rugby league for BBC Radio 2, a TV series of hospital visits entitled A Spoonful of Sugar in 1967/8 and a Sport of the Day Saturday BBC2 series in 1965. Keith Macklin was also a presenter on both BBC TV Look North in the mid 1960s and became a regular contributor to BBC Radio Merseyside in its infancy, covering sport. In 1969, he was the first presenter of the BBC programme Pot Black, and shortly afterwards he joined Yorkshire Television as a football commentator, where he would remain until 1976. He also commentated on the 1974 World Cup for the ITV network, covering the only match ever played between the West and East German national sides, and presented the religious series Junior Sunday Quiz for YTV. Subsequently, he worked for Red Rose Radio and reappeared as a reporter for ITV's The Goal Rush in 2001.
His works include:
- The Rugby League Game (1967)
- The History of Rugby League (1974) ISBN 0-09-120780-0
- The Story of Rugby League (1984) ISBN 0-09-158411-6
- Shenton, Kenneth (1 October 2009). "Keith Macklin obituary". guardian.co.uk. London. Retrieved 16 October 2009. CS1 maint: discouraged parameter (link)
- Many issues of the Northern edition of Radio Times, including the 13-19 May 1961 issue where he is listed commentating on the Rugby League Challenge Cup final
- Genome listings