Prior to debut, Seventeen also appeared in the reality TV show Seventeen Project: Debut Big Plan, broadcast on MBC between May 2–26, 2015. The show concluded with the group's debut showcase

                                                   

   Seventeen debuted on May 26 with a live showcase televised by MBC. They were the first male K-pop group to debut with a one-hour live showcase on a major broadcasting channel,.Three days later, their first album 17 Carat  was digitally released.

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  17 Carat  became the longest-charting K-pop album of the year in the US  and was the only rookie album to appear on Billboard's "10 Best K-pop Albums of 2015" chart. 

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  On September 10 their second album Boys Be was released, which would later become the highest selling rookie album of 2015. The album's success earned the group awards at the Golden Disk Awards, Seoul Music Awards and Gaon Chart K-Pop Awards. Seventeen was also the only K-pop group on Billboard's "21 Under 21 2015 :  Music's Hottest Young Stars" list.

 

  Seventeen held a four-date concert series titled 2015 Like Seventeen – Boys Wish from the 24th to the 26th of December as an end-of-year celebration in Seoul.. After the concerts' success, Seventeen held two related concerts the following February in 2016, entitled Like Seventeen – Boys Wish Encore Concert.