2008–14: Career beginnings

In 2008, he was chosen as a member of the group Shinee. The 5-member boy group debuted on May 25, 2008, on SBS's Inkigayo.[2] Jonghyun debuted as a songwriter when writing the Korean lyrics to Shinee's fourth promotional single, "Juliette", which was the featured on their second mini album, "Romeo", released in May 2009. On November 6, 2009, labelmate Yesung of Super Junior made a surprise appearance on KBS Music Bank with Shinee in place of Jonghyun, who was recovering from influenza, in a performance of "Ring Ding Dong".[3]

Jonghyun went on to participate in the writing of two songs on Shinee's second Korean studio album, "Lucifer", which were released on July 2010. The first, "Up & Down", was co-written with Misfit, with the rap being written by groupmate Minho. The second, "욕 (Obsession)", was completely written by Jonghyun, minus Minho once again working on his own rap. In October 2010, Jonghyun was one of twenty idols from various South Korean groups that recorded the song "Let's Go" with the purpose of increasing public participation in the 2010 G-20 Seoul summit. He provided his vocals along with other labelmates, such as: Super Junior's Sungmin, Girls' Generation's Seohyun and f(x)'s Luna.[4] In November 2010, it was revealed by S.M. Entertainment that Jonghyun, along with TRAX's Jay, Super Junior's Kyuhyun, and rookie singer, Jino, would be participating in a project group together under their label. The group was revealed to be named SM the Ballad. Rather than pop, the subunit focused more on releasing songs from the ballad or the R&B ballad genre.[5] The group released their debut mini album, Miss You, on November 29, 2010, and debuted on November 28, 2010, on SBS's Inkigayo with their lead single that shared the same title as the mini album. After finishing the promotions for their first track, the subunit continued on with follow up promotions; the focus was another track on their album entitled "Hot Times".[6]

In June 2011, Jonghyun joined KBS's Immortal Songs 2, where singers render their own versions of old songs from music legends and winners are selected by voting.[7]In 2012, Jonghyun co-wrote the lyrics to the song "알람시계" (Alarm Clock)" with Minho, a song about wishing to wake up from the nightmare of a past break-up,[8] and wrote the lyrics to "늘 그자리에 (Honesty)" which was described as a song written for the fans who had stayed by their side with unchanging love until that point. Both songs were featured in the mini album "Sherlock". For Shinee's Misconceptions series (which is made up of two full albums and a repackage), Jonghyun wrote the lyrics to: "Spoiler", "오르골 (Orgel)", "Dangerous (Medusa II)" (which was co-written with Jo Yun Kyeong), "버리고 가 (Better Off)" and "너와 나의 거리 (Selene 6.23)", the last which was written after Jonghyun drew inspiration from witnessing a super moon in June 2013. In October 2013, Jonghyun wrote the lyrics to "상사병 (Symptoms)" which was featured in Shinee's fifth mini album, "Everybody". In October 2013, Jonghyun debuted as a composer of the track "우울시계 (A Gloomy Clock)" which was featured in IU's third Korean album, "Modern Times". The song, which Jonghyun gifted to IU as a friend, was also co-written by Jonghyun and dubbed a duet.[9] Two months later in December "Red Candle", which was also composed and written by Jonghyun, was released by Son Dam Bi.[10]

After four years of hiatus for SM the Ballad, S.M. Entertainment announced that the group would be making a comeback on February 4, 2014, with a new line-up; Jonghyun was the only member from the original line-up.[11] It was further revealed that Jonghyun would be participating in a duet with Girls' Generation's Taeyeon called "Breath," which they also promoted together.[12] In July 2014, Jonghyun debuted a special corner called "Blue Night Lyrics, That Man's Composition".[13] He announced the project in June 2014, tweeting:

Jonghyun also contributed with the production for Taemin's first mini album, Ace, composing and writing the track called "Pretty Boy", released in August 2014.[14]