Meagher was born and raised on a sheep and cattle station in Queensland, before attending a boarding school on the Gold Coast from the age of nine.

[3] His other film appearances include The Chant of Jimmie Blacksmith (1978), Newsfront (1978), My Brilliant Career (1979), The Shiralee (1987),[1] Mad Dog Morgan (1976), Money Movers (1978), The Odd Angry Shot (1979), The Earthling (1980), Hoodwink (1981), Runaway Island (1982), and The Fire in the Stone (1984).

[4] Meagher became "a much in demand character actor", with his early television roles including Matlock Police, Ben Hall, Rush, Certain Women, Pig in a Poke, The Restless Years, Glenview High, The Oracle, Kingswood Country, Cop Shop, Skyways, Sporting Chance, Holiday Island, and Bellamy.

[3] Marie Ussher of TV Week observed that Meagher was often cast as the "baddie" or tough, ruthless characters in his early career.

During the same period, he also made an appearance in A Country Practice as alcoholic, pub owner Wally, followed by a role in television film The Blue Lightning for America's CBS network.

[5] Meagher joined the cast of soap opera Home and Away in 1987 and has appeared in the role of Alf Stewart continuously since the first episode aired in January 1988.

[6] Meagher also appeared in the 1988 children's series The True Story of Spit MacPhee, along with John Bach and Elspeth Ballantyne.