He was a founding member of the bands The Easybeats and Flash and the Pan, and was one-half of the songwriting and production duo Vanda & Young with his long-time musical collaborator Harry Vanda, with whom he co-wrote the international hits "Friday on My Mind" and "Love Is in the Air", the latter recorded by John Paul Young (who is unrelated).

He was also one of the producers of early work by the Australian hard rock band AC/DC, formed by his younger brothers Malcolm and Angus Young.

In 1940, William joined the Royal Air Force serving in World War II as a flight engine mechanic.

[2][3] Also aboard were George's eldest brother Stephen (24 June 1933 – 1989) and his wife and two sons, one of whom was Stevie Young, who later joined AC/DC to replace his uncle, Malcolm Young), his only sister, Mrs Margaret Horsburgh (2 May 1935 – 2019) and her husband and son, and brother, William Jr (born 15 December 1940) and his wife.

[4]: 6–7  Another elder brother, Alex (28 December 1938 – 4 August 1997), stayed in the UK, and was later a member of London-based group Grapefruit.

[3] The William Young family moved into a semi-detached house at 4 Burleigh Street in the Sydney suburb of Burwood.

Malcolm Young, his younger brother, attended the same school for a time until the family moved to Burwood.

[8][9] All of the members had a connection with Villawood Migrant Hostel, and their early rehearsals were held in its laundry room.

Early top 10 hits on the Australian singles chart for the Easybeats were co-written by Young with bandmate Wright:[8] "She's So Fine"[11] (No.

[9][19] They provided pop and rock songs for other recording artists, and for themselves under various stage names: Paintbox, Tramp, Eddie Avana, Moondance, Haffy's Whiskey Sour, and Band of Hope.

[5][19] One studio-based group, Marcus Hook Roll Band, was joined in 1974 by Young's brothers, Malcolm and Angus.

[5][9] He also made the suggestion that "It's a Long Way to the Top" should include bagpipes after having heard that Bon Scott had played in a pipe band, not knowing that he was actually a drummer.

[19][21] The group's ninth single, "Waiting for a Train" (December 1982), had lead vocals by their former bandmate, Stevie Wright.

In May 2001, the Australasian Performing Right Association (APRA) in May 2001 conducted a survey of music industry personnel to determine, the "ten best and most significant Australian songs of the past 75 years.

[30] At the ARIA Music Awards of 2005, the Easybeats, including Young and Vanda, were inducted into the Hall of Fame.