Leclercq's first EP The City, was released in 2012. His debut studio album Adventure is set to be released on 30 March 2015, and will be supported by a 22-stop North American tour.
Leclercq started composing music at the age of 11, producing hands-up under the name of "Deamon" until 2010 when he began producing house music under his current name, Madeon, which is an anagram of his previous nickname. He won a remix competition for "The Island" by Pendulum the same year.
He went on to remix other electronic artists' tracks the following year. A clip of him performing his mash-up "Pop Culture", uploaded to YouTube on 7 July 2011, propelled him to international fame. It featured samples from thirty-nine songs mixed together on-the-fly using a Novation Launchpad. The clip quickly went viral and reached over six million views in just a few days.
During live performances, apart from the Launchpads, he also uses Novation's Zero SL MKII, FL Studio, and Ableton Live. His first live performance was in Paris in April, 2011 where he was a support act to Yelle, and his UK debut was at The Nest in Dalston, London where he performed alongside the likes of Jacques Lu Cont.
Leclercq has been featured several times on 15 Minutes of Fame, a segment of Pete Tong's radio show on BBC Radio 1, with both his debut single "Icarus" and his remix for deadmau5's "Raise Your Weapon" given their first full play on the show. His live recorded performance debut was for Pete Tong's BBC Radio 1 gala event in Hull on 27 January 2012, where he played a 20 minute-long set.
A debut EP was scheduled to be released at the end of 2011, but then cancelled in favour of multiple singles. The first single, "Icarus", was released on 24 February 2012 on his independent label popculture.
As a sign of his rapid rise to international fame, in 2012, he was invited to play four major American festivals, the Ultra Music Festival in Miami, Coachella in California, Lollapalooza in Chicago, and Electric Daisy Carnival in New York, as well as several UK dance music festivals, including the Dance Arena at Radio 1's Hackney Weekend 2012; he also provided support for Swedish House Mafia's headlining set at the Milton Keynes Bowl. Leclercq was listed at number 54 on DJ Mag's Top 100 DJs list in 2012.
Many of his songs have been used in media franchises: "Icarus" was featured in the US show Dancing with the Stars in May 2012 and 21 May 2013 (finals with Aly Raisman) and on the in-game soundtrack of Forza Horizon; "Finale" and "Imperium" have been featured in EA Sports' FIFA 13 and FIFA 15 respectively. Finale has also been included in the opening cinematic of PlayStation All-Stars Battle Royale; "The City" appears in Need for Speed: Most Wanted and "Technicolor (Club Extended)" in Need for Speed: Rivals. "Finale" and Leclercq's remix of "The Night Out" by Martin Solveig were featured on the official soundtrack of ESPN's 2013 Winter X Games event in Tignes, France and both received several plays on air. "Finale" continues to be used as the bumper music for X Games broadcasts.
He toured with Lady Gaga as an opening act during her Born This Way Ball.Leclercq has cited The Beatles and Daft Punk as his greatest musical influences. Madeon released a new single on 3 August 2013 titled "Technicolor." Madeon worked with Lady Gaga on three tracks, "Gypsy", "Mary Jane Holland", and "Venus" on her 2013 album ARTPOP.
On 25 February 2014, Leclercq released a track available for a free download on his website called "Cut The Kid", claiming that it was created circa 2011 or 2012.