Giscombe was born in Wandsworth, London, and was a backing vocalist with Linx between 1980 and 1982.

When turning towards a solo career, he was first billed simply as Junior and he scored a #7 hit in the UK Singles Chart in 1982, with “Mama Used to Say”. His follow-up single, “Too Late” also made the Top 20 in the UK. “Mama Used to Say” was also a Top 40 Pop hit and Top 5 R&B in the United States, earning him a “Best Newcomer” award from Billboard magazine.

Sometime (most likely) around 1984 and 1985, Junior Giscombe recorded (and very possibly co-wrote) an unknown number of songs with Phil Lynott, the former leader, vocalist and bass player of hard rock band Thin Lizzy. Lynott died in January 1986 and the songs were never officially released. Most remain as demos, but one of the songs, “Lady Loves to Dance”, was mastered and nearly released before being pulled by the record company. Some of the songs are available on YouTube, including “What’s the Matter Baby” (Giscombe provides backing vocals) and “Time (and Again)” (Giscombe shares vocals with Lynott).

After a period outside the charts, he made a brief return to the Top 10 in 1987 when he sang a duet with Kim Wilde on “Another Step (Closer to You)”. He also became involved with the formation of Red Wedge in 1986 with Billy Bragg, Jimmy Somerville and Paul Weller, and had been a part of The Council Collective with The Style Council, Jimmy Ruffinand others for the 1984 fundraising single, “Soul Deep” and in 1992 appeared on stage at the 1992 Labour rally in Sheffield singing Curtis Mayfield’s “Move On Up”. Later Giscombe became better known as a songwriter for various artists, including Sheena Easton.

Giscombe is the uncle of British comedian Richard Blackwood, who sampled “Mama Used to Say” on his single “Mama – Who Da Man” in June 2000.