Singer Sung Si-kyung marked the finale of his 25th debut anniversary in 2025 with a year-end concert held over four days with his fans. Sung Si-kyung held his solo concert "2025 Sung Si-kyung Year-End Concert " from December 25 to 28 at the KSPO DOME (Olympic Gymnastics Arena) in Olympic Park, Seoul. The concert proved Sung Si-kyung's popularity by selling out all seats for all four shows as soon as the tickets were released.

Sung Si-kyung captivated the audience with his sweet and delicate voice during the performance. The stage was designed in a 360-degree structure to maximize communication with the audience. Lyrics for all songs were visible from anywhere, creating an environment where the audience could sing along. Sung Si-kyung appeared in a white suit setup and opened the show with "Like the First Time." He said, "I worked hard to prepare this performance, and I am really happy to see so many people in person. Thank you for being here with me."

The concert proceeded with a solid setlist composed of Sung Si-kyung's representative songs. Starting with "We Go Well Together," followed by hits such as "It Would Be Nice," "Can't Bear It...," "On the Street," "One More Goodbye," "Goodbye My Love," "On Some Day, With Some Heart," "Every Moment of You," "Solar System," and "Hee-jae." Each time these songs were performed, the audience sang along in unison. Sung Si-kyung's soft voice deeply moved the audience.

Videos of senior and junior colleagues who have worked with Sung Si-kyung were also shown during the concert. Park Jin-young praised him as "a singer who moves the heart," while Kim Hyung-seok said, "Watching his exceptional talent, I thought he would be a singer who lasts a long time." Yoon Jong-shin recalled, "Thank you for choosing the title track 'On the Street.' This song gave me confidence as a composer."

Sung Si-kyung delighted the audience with a reinterpretation of G-Dragon's "PO₩ER." Additionally, glamorous guests such as Dynamic Duo, Daesung, and Hwasa appeared to heighten the excitement of the concert. On the 25th, Dynamic Duo performed "Smoke," "Guilty," "Go Back," "Are You Sleeping," and "Friday Night." On the 26th, Daesung performed "Over the Limit," "Universe," and a medley of Big Bang's hits. On the 27th and 28th, Hwasa moved the audience with "Good Goodbye," "Don't Do It," and "Maria."

In the latter part of the concert, Sung Si-kyung continued the excitement by passionately singing "Smile Angel" and "You Were Moving." For the encore, he performed "Two People" and "The Way to Me," sharing a special moment with fans to celebrate his 25th debut anniversary. Fans left comments such as "I was happy to hear an excellent national treasure-level voice," "This was a perfect Christmas this year," and "This concert deserves a star in Sung Si-kyung's 25th anniversary chronicle," promising to meet Sung Si-kyung again.