Born in Lund, Måns Zelmerlöw is the son of Birgitta Sahlén, a professor at Lund University, and surgeon Sven-Olof Zelmerlöw. Zelmerlöw studied music in high school in Lund and was part of a school choir project. In 2002, he played one of the brothers in the musical Joseph and the Amazing Technicolor Dreamcoat at Slagthuset in Malmö.

On 26 December 2004, Zelmerlöw and his family survived the Indian Ocean earthquake while on vacation in Khao Lak, Thailand.

Zelmerlöw first entered the public eye in 2005, when he took part in season 2 of the Swedish version of Idol, which was broadcast on TV4. He came in fifth place overall, and was eliminated on 11 November after eight weeks on the show. He had placed in the bottom three once and the bottom two twice.

Zelmerlöw took part in the first season of Let’s Dance in 2006, partnering with Maria Karlsson. They won the competition, defeating singer Anna Book in the final.

In November 2006, it was announced that Zelmerlöw would compete in Melodifestivalen 2007, Sweden’s national final for the Eurovision Song Contest 2007, to be held in Helsinki, Finland. He competed with the song “Cara Mia” in the third semi-final on 17 February 2007 in Örnsköldsvik, and progressed to the final, which was held on 10 March at Globen in Stockholm. There his performance of “Cara Mia” finished in third place behind winners The Ark and runner-up Andreas Johnson. “Cara Mia” was released as a single and Zelmerlöw’s debut album Stand by For… followed shortly after. The album reached number one in Sweden and was certified platinum by IFPI. Four singles were released from the album, all of which reached the top 50 in Sweden. Stand by For… was also released in Poland in September 2007.

On 5 October 2007, Zelmerlöw was the presenter of Lilla Melodifestivalen on SVT. He also participated in the musical version of Footloose, playing Tommy. The musical was performed in both Gothenburg and Stockholm. In 2008, he participated in the Diggiloo tour along with singers Lasse Holm, Linda Bengtzing, Lotta Engberg, Thomas Pettersson, Molly Sandén and Nanne Grönvall.

On 18 November 2008, it was announced that Zelmerlöw would again compete in Melodifestivalen, this time with the song “Hope & Glory”. The 2009 contest featured many former entrants, including Sarah Dawn Finer, Sofia, BWO and Amy Diamond. He took part in the second semi-final on 14 February 2009, and again progressed to the final on 14 March at Globen. “Hope & Glory” ultimately placed fourth, despite receiving the most votes from the jury.

In 2008, Zelmerlöw went back to the studio to work on his second solo album, MZW, which was released in late March 2009. It was certified gold by the IFPI and reached number one on the Swedish album charts. The album was also released in Poland. In 2009 he played a summer tour of Sweden performing songs from both albums.

Between 2008 and 2011, he was in a relationship with the Swedish singer and model Marie Serneholt, a former member of the Swedish pop band A-Teens. In 2016, Zelmerlöw began dating English actress Ciara Janson and they later announced their engagement. In December 2017, Zelmerlöw announced that they were expecting a child together. A few weeks later, he confirmed that the child would be a baby boy. The couple live in London. On 25 May 2018 he announced via social media that Ciara had given birth to their son, Albert. The couple married on 5 September 2019.

On 10 November 2009, it was announced that Zelmerlöw would host Melodifestivalen 2010, alongside Dolph Lundgren and Christine Meltzer. He hosted the first semi-final and the final with Lundgren and Meltzer, and the remaining semi-finals with only Meltzer. In the opening of the Second Chance round, he performed the Duran Duran song “A View to a Kill”, and in the final he sang the Survivor song “Eye of the Tiger” with his fellow presenters. He also acted as Romeo in the musical Romeo and Juliet, and guest starred in the talent show Jakten på Julia at SVT, where Lisette Pagler won the role as Juliet. The musical had its premiere in December at Göta Lejon.

In January 2011, Zelmerlöw was announced as the replacement for Anders Lundin as presenter of Allsång på Skansen, broadcast on SVT. He also presented the show in 2012.

In March 2013, Zelmerlöw revealed plans for his third studio album, Barcelona Sessions, unveiling a new single, “Broken Parts”. He also performed a new track on Swedish television called “Run for Your Life”. In September 2013, Zelmerlöw unveiled the second single from the new album, called “Beautiful Life”, and performed another album track entitled “Parallels”. The album was released on 5 February 2014, preceded by “Run for Your Life”.

Zelmerlöw participated as a songwriter in Melodifestivalen 2013, co-writing the song “Hello Goodbye”, performed by singers Erik Segerstedt and Tone Damli. The song made it to the second-chance round. In late 2013, he had the lead role in the new version of the Swedish musical Spök along with Loa Falkman, Sussie Eriksson and Lena Philipsson.

In March 2014, while a guest on Swedish cooking show Pluras kök, Zelmerlöw commented that he considered homosexuality an avvikelse (English: deviation). On the show, he said he did not think there was anything wrong with homosexuality, but that it is not natural biologically, since it does not lead to reproduction. He later apologised repeatedly for his remarks, claiming that they were a miscommunication. After his Melodifestivalen win a year later, the incident came under international media scrutiny, prompting members of gay, Swedish and Eurovision media to come to Zelmerlöw’s defence. He later said that “if I got that feeling” he would date a man.

In 2015, Zelmerlöw again participated in Melodifestivalen with the song “Heroes”, which scored 288 points and won the final. In the same festival, he co-wrote the entry “Det rår vi inte för”, which was performed by Behrang Miri, and which made it to the second-chance round.

On 11 May 2015, Zelmerlöw revealed the artwork and track list for his fourth studio album Perfectly Damaged, which was released on 5 June 2015. On 17 May, Zelmerlöw performed the song “Heroes” in Belgrade during the first live show of X Factor Adria.

In May 2016, he co-hosted Eurovision Song Contest 2016 in Stockholm with Swedish TV presenter Petra Mede. During the three shows Måns performed his winning song “Heroes”, his new song “Fire in the Rain”, and two musical sketches both co-written with Edward af Sillén, “Story of ESC” and the acclaimed “Love, Love, Peace, Peace” with Petra Mede.

In October 2016, he was featured in the TV series Chevaleresk with host Alexander Wiberg. It was broadcast on TV6 .

Zelmerlöw’s seventh studio album, Chameleon, was released in December 2016. The lead single “Hanging on to Nothing”, had been released the previous August. The song failed to chart on the Official Swedish Singles chart, but peaked at number 2 on the Heatseekers chart. On November 5, 2016, the French version of “Hanging on to Nothing” was released titled “Rien que nous deux” (“Only the two of us” in English).

In 2017, Zelmerlöw was the co-commentator for SVT at the Eurovision Song Contest 2017 alongside Edward af Sillén, Zelmerlöw also appeared in a sketch involving the three hosts; Oleksandr Skichko, Volodymyr Ostapchuk, and Timur Miroshnychenko.

On 16 November 2017, it was announced that Zelmerlöw would co-host BBC’s Eurovision: You Decide with Mel Giedroyc on 7 February 2018 at the Brighton Dome. He opened the show with a medley of ABBA hits, duetting with UK Eurovision entrant Lucie Jones.

In 2018 his song “Happyland”, released on the Chameleon album, was chosen by confectionery company Kinder to celebrate its 50th anniversary through commercials broadcast in European countries such as Germany and Italy.

On 1 March 2019 Zelmerlöw and Swedish singer Dotter released the song Walk With Me.

Zelmerlöw announced in May 2019 that he would release the songs Better Now and Grow Up to Be You.

On 18 October 2019 Zelmerlöw released his eighth studio album, Time. As a third single, the song One has been released on 21 November 2019 for digital download.

Zelmerlöw was part of the jury of Eurovision: Australia Decides 2020 and also performed the single Walk With Me, which has been re-released with Australian singer Dami Im on 6 February 2020.

Zelmerlöw and Morgan Sulele released the Single Gamle Dager on 10 April 2020. The song contains Norwegian and Swedish lyrics.

As the fourth single from Zelmerlöw´s album Time the song On My Way has been released on 24 April 2020.