He rose to fame in the 1980s as the lead singer of the new wave band Spandau Ballet and launched a solo career following the group's split in 1990.

[6] Hadley co-founded Spandau Ballet in 1976 as the Cut, with Gary Kemp, Steve Norman, John Keeble and Michael Ellison, all of whom were students at Dame Alice Owen's Grammar School.

[7] As a member of Spandau Ballet, Hadley went on to enjoy international success in the 1980s, including hits such as "True", "Gold" and "Through the Barricades", as well as appearing at Live Aid in 1985.

[10] In his book on the New Romantics, music journalist and author Dave Rimmer described his voice "like a foghorn—if a foghorn could be imagined trying to emulate both [Frank] Sinatra and [David] Bowie".

"[15] After Spandau Ballet disbanded, Hadley pursued a solo career, signing to EMI and recording his first album, The State of Play, in 1992.

In May 1997, Hadley signed a joint deal with PolyGram TV, and released his next eponymous solo album, which included covers and songs that were chosen to match his voice.

[20] Following a number of successful collaborations with other house artists and DJs, Hadley became the subject of some newfound respect in the 2000s, rooted in an "ironic" appreciation for Spandau Ballet.

[21] This saw him begin work on album of solo euro-house material, which remains unreleased, after signing a deal with European label Frontera Recordings.

Back on home soil, fearing that the project was too far removed from his origins with Spandau Ballet, Hadley released an EP of four new songs, Get So Lonely, on his own label, Blueprint Recordings, in the summer of 2001.

Meanwhile, Debut and Obsession, two live albums featuring recordings taken from a performance in Cologne in 1992 and Ronnie Scott's in 1999 respectively, were released in limited numbers by small-budget labels.

Although a collaboration with Marc et Claude followed in April 2002, no further singles from the house album were released; and by the autumn of 2002, Hadley had signed up to participate in the new ITV reality series Reborn in the USA.

Hadley beat ten other artists, including Peter Cox, Michelle Gayle, Elkie Brooks, Sonia, and Leee John,[23] to win the prize of a recording contract with Universal Music.

[24] The resulting album was True Ballads, a compilation of three re-recorded hits from the Spandau Ballet days, ten tracks from his 1997 self-titled album, and two new songs: a cover of "I Can't Make You Love Me", which he performed on the show, and "After All This Time", the theme song from the BBC drama series Down to Earth, which ran from 2000 until 2005.

In 2013, Hadley and 1980s chart peers Kim Wilde, Bananarama and Go West set a new world record for Comic Relief when they performed the highest ever gig, singing on a Boeing 767 aeroplane at 43,000 ft (13,000 m).

[28] In 2014, Hadley took part in the prime-time RAI TV show La Pista as team leader of the Tacco 10 female dance troupe.

Later in the year, Hadley was one of the featured vocalists on the single "The Best Christmas (in Lockdown)", a charity assemble of around one-hundred celebrities recording for the Hertfordshire-based Electric Umbrella organisation.

Hadley appeared, sang and gave advice in Pinoy Dream Academy, a singing reality show in the Philippines.

Hadley is a patron of the UK Huntington's Disease Association,[43] Shooting Star Chase and The Lowe Syndrome Trust.

[44] In December 2019 it was announced that he had been awarded an MBE in the New Year Honours for charitable services to Shooting Star Chase Children's Hospice Care.