Chanyeol became a trainee under SM Entertainment after winning second place in the 2008 Smart Model Contest. While training under S.M., he began to turn his focus towards rapping. Prior to his debut, Chanyeol made cameo appearances in TVXQ's "HaHaHa Song" music video and Girls' Generation's "Genie" music video in 2008 and 2010 respectively.
Chanyeol became the last Exo member to be officially introduced to the public on February 23, 2012. The group official debuted on April 8, 2012 with the extended play Mama. In April 2012, he made a guest appearance in Girls' Generation-TTS's music video for their debut single "Twinkle". In October 2013, Chanyeol joined the cast of SBS's reality TV show Law of the Jungle during its filming in Micronesia. He also composed and recorded an original Soundtrack titled "Last Hunter" for the show in 2015 after rejoining the show.
In 2014, Chanyeol wrote the rap for the Korean version of the track "Run" from Exo's second extended play Overdose and was featured in label-mates Henry's second extended play and Zhou Mi's debut EP. In May 2014, he became a regular cast member of the first season of SBS's reality TV show Roommate. He left the show in September 2014 due to schedule conflicts.
In April 2015, Chanyeol made his big screen debut with a supporting role in the South Korean film Salut d'Amour, which starred Park Geun-hyung and Youn Yuh-jung. He later starred as the male lead alongside Actress Moon Ga-young and fellow Exo members in the web-drama Exo Next Door. In June 2015, Chanyeol, along with fellow Exo members Chen and Lay, co-wrote the Korean version of the track "Promise" from Love Me Right, the re-released version of Exo's second studio album. He later wrote the rap for "Lightsaber", Exo's promotional single for Star Wars: The Force Awakens, which was subsequently included in their third extended play Sing for You.
In April 2016, Chanyeol wrote and performed the rap for the song "Confession" from Yesung's debut extended play. In Exo's third studio album Ex'Act, which was released in May 2016, he co-wrote the lyrics for the track "Heaven". In June 2016, Chanyeol starred alongside Yuan Shanshan and label-mate Seohyun in the South Korean-Chinese film So I Married an Anti-fan. He and Yuan Shanshan also recorded a duet titled "I Hate You" as the theme song for the movie. In October 2016, Chanyeol and American R&B singer Tinashe were featured in American hip hop group Far East Movement and American electronic musician Marshmello's song "Freal Luv". In December 2016, Chanyeol and South Korean singer Punch collaborated on an original Soundtrack titled "Stay With Me" for tvN's drama Guardian: The Lonely and Great God. The song reached number three on South Korea's Gaon Digital Chart.
In September 2017, Chanyeol was invited to attend Tommy Hilfiger's fashion show in London.