Years before she would debut as the youngest member of one of K-pop's most successful fourth-generation girl groups, Lee Hyun-seo made her first television appearance in the most serendipitous way. In August 2009, the SBS variety program "One Night of TV Entertainment" (Hanbam) was filming a street segment with actress Han Hyo-joo, who had just achieved breakthrough success with the drama "Brilliant Legacy."1 A two-year-old Hyun-seo, accompanying her mother to take out the trash, caught the actress's eye. Han Hyo-joo, charmed by the toddler's cuteness, asked for a kiss on the lips—which the young child readily gave, creating a viral moment that would resurface twelve years later when she debuted as Leeseo of IVE.1

Speaking on the popular YouTube show MMTG in April 2022, Leeseo confirmed the footage was indeed her: "Yes, that's right. That is me when I was little. I kissed Han Hyo-joo sunbaenim," she said with a laugh. She admitted she was too young to remember the encounter personally—her mother had told her about it as she grew older.2 The clip seemed to foreshadow a life destined for the spotlight.

Leeseo's formal introduction to the entertainment industry began during her second year of elementary school when she participated in a piano competition. There, an SM Entertainment casting staff member noticed her and invited her to audition for the company's Kids Model program.3 In 2016, at just nine years old, she won a spot as part of SM Entertainment's Kids Model 1st Generation, beating out 400 other candidates in a highly competitive selection process.3 During this period, she participated in various modeling activities, developing the stage presence and confidence that would later serve her idol career.

The trajectory that would lead her to IVE began in 2019. While shopping with her parents at the Shinsegae Department Store in Gangnam, twelve-year-old Hyun-seo was waiting for a drink at a café when a Starship Entertainment executive approached her family.4 The casting official later remarked that he "could not forget the glittering eyes" of the young girl.5 Though she had never dreamed of becoming an idol, she followed her father's suggestion to pursue the opportunity.5

What followed was approximately two and a half years of intensive training. The regimen at Starship Entertainment was notoriously rigorous, involving sessions that could run from morning until midnight, up to six days per week.6 Leeseo developed unique practice techniques, including rehearsing facial expressions while washing in the bathroom and eating sour foods to perfect her signature quick winking.6 The company's comprehensive curriculum also included selfie lessons with daily feedback and short-form content creation training—skills that would prove invaluable in the age of social media-driven K-pop.6

On November 8, 2021, Leeseo was revealed as the sixth and final member of IVE—Starship Entertainment's first girl group since WJSN in 2016.7 The Korea Herald covered the group's debut showcase on December 1, 2021, where the six members—comprising Yujin, Gaeul, Wonyoung, Liz, Rei, and Leeseo—"threw their glitzy hats into the ring" with their debut single album "Eleven."7

At 14 years, 9 months, and 10 days old, Leeseo became one of the youngest idols to debut in mainstream K-pop outside of "kiddol" groups.8 On December 3, 2021—just two days after debut—she set a record as the youngest female idol to appear on a music show, though this record would later be surpassed by other artists.8 Her young age created unique circumstances: until February 2022, South Korean broadcasting regulations prohibited her from appearing on radio programs that aired after 10 PM, and any recordings that exceeded that time required her to return home.5

IVE's debut shattered industry expectations. "Eleven" earned the group their first music show win on MBC M's Show Champion on December 8, 2021—exactly one week after debut—tying the record for the fastest first win by a girl group.9 The single went on to win 13 music show trophies, while the debut album recorded the highest first-week sales for a girl group debut, selling over 152,000 copies in its first week.10

The year 2022 proved transformative for IVE and solidified Leeseo's place in K-pop history. The group's second single "Love Dive," released in April 2022, became the best-performing single of the year in South Korea, topping the Circle Digital Chart for four weeks.11 At the 2022 Melon Music Awards in November, IVE won the Daesang (Grand Prize) for Song of the Year—just 360 days after debut, making them the third-fastest girl group to win a grand prize.11

This victory made Leeseo, at 15 years old, the youngest idol ever to win a Daesang at the Melon Music Awards, breaking the previous record held by 2NE1's Minzy.12 Days later at the 2022 MAMA Awards, the group claimed Song of the Year and Best Dance Performance (Female Group), cementing their status as one of the most successful rookie groups in K-pop history.13

The accolades continued to accumulate. IVE became only the fourth group in K-pop history to win both a rookie award and a daesang in the same year, following 2NE1, Miss A, and aespa.11 Their third single "After Like" achieved a Perfect All-Kill—simultaneously topping real-time, daily, and weekly charts across all major Korean music platforms—and went on to win 14 music show trophies, the most for any song that year.14

As IVE continued their ascent, Leeseo began carving out her individual identity. In February 2024, she released "May Lily," her first solo original soundtrack for the Naver Webtoon series "I'm the Queen in This Life."15 The dark, ethereal track showcased a different dimension of her vocals—the distinctive husky yet dreamy tone that fans had long admired. The song marked Leeseo's first solo music project since her 2021 debut and demonstrated her capability as a standalone artist.15

Two months later, in April 2024, SBS announced Leeseo as the new MC for their flagship music program Inkigayo, alongside ZEROBASEONE's Han Yujin and actor Moon Sung Hyun.16 The trio formed what became known as the "Maknae MCs," boasting the youngest average age in Inkigayo history. Through her agency, Leeseo expressed her gratitude: "It's an immense honor to take on the role of MC for Inkigayo. I'm thrilled for this precious opportunity and will strive to bring vibrant energy to the viewers each week."16

Her tenure at Inkigayo became a period of remarkable growth. Leeseo impressed audiences with her flawless performances in weekly skit concepts and earned the nickname "K-pop Challenge Vending Machine" for her ability to master returning artists' choreography with impressive accuracy in just a few hours.17 Her hosting skills and quick wit earned strong affection from viewers, with her photos on the SBS Play Inkigayo page becoming the most viewed in the program's history.18 After one year and seven months, she concluded her MC duties in December 2025, stating: "Sundays felt like a gift to me... I will return as IVE's Leeseo with even better performances."17

Leeseo's solo endorsement career began in August 2023 when American outdoor brand The North Face selected her as their Korean ambassador alongside ASTRO's Cha Eun-woo.19 The brand officially cited her "young and healthy energy and luxurious yet unique charm" as matching their image perfectly, noting that she had become a "wannabe" (aspiration figure) for the "Zalpha" generation—those born at the intersection of Generation Z and Generation Alpha.19 This marked Leeseo's first solo advertising contract since her debut, establishing her commercial appeal independent of the group.19

Her endorsement portfolio expanded significantly through 2025. In August, Korean beauty brand The Saem announced her as their brand model, followed by National Geographic Apparel's "School in Style" campaign in December.20 These partnerships reflected industry recognition of her influence among younger demographics—a valuable market segment in the Korean beauty and fashion industries.

Within IVE's vocal lineup, Leeseo has cultivated a distinctive sound characterized by what fans describe as a "candy voice"—a husky yet dreamy, ethereal tone that stands out particularly in the mid to high-range parts of the group's songs.21 Her goal, she has stated, is to develop vocals so distinctive that listeners immediately recognize it as "Leeseo's voice."5 This quality has been particularly evident in her bridge delivery on tracks like "I Am," where she performs the line "As I walk, it becomes my path" with precision that has earned praise during encore performances.5

Her performance capabilities extend beyond vocals. As part of IVE's dance line alongside Yujin and Gaeul, Leeseo handles technically demanding choreography, including the signature spin move in "I Am" and the intricate opening sequence of "Baddie."21 During Rei's health-related hiatus in 2023, she covered the Japanese member's rap parts despite not being part of IVE's official "Rap Mates" unit—demonstrating her versatility and readiness to support her members.8

Leeseo's journey has required balancing the demands of a thriving K-pop career with her education. After graduating from Bangbae Middle School in 2022, she was accepted into Hanlim Multi Arts High School's Broadcasting and Entertainment department—a notable choice given that most Starship Entertainment trainees and idols typically attended Seoul Performing Arts High School.22 In keeping with Starship's tradition of prioritizing education for their youngest artists, she has occasionally missed group schedules to take midterm exams—a practice previously observed with other agency maknaes.8

In November 2025, as she entered her final year of high school, Leeseo announced she would not be taking the College Scholastic Ability Test (CSAT) for 2026, choosing to focus fully on IVE's activities.22 This decision came as the group launched their second world tour "Show What I Am" and continued releasing new music with their albums "IVE EMPATHY" and subsequent releases.

At eighteen years old, Leeseo has accumulated achievements that belie her age. From an accidental television appearance as a toddler to winning the industry's highest honors as a teenager, her trajectory exemplifies the K-pop system's capacity to identify and nurture exceptional talent. Her selection by Starship Entertainment was driven, according to Vice President Seo Hyun-joo, by her "seriousness and passion"—qualities that caught the company's attention during evaluation.23

As IVE continues to solidify their position as one of K-pop's leading groups—having sold over 12 million album copies and embarked on successful world tours—Leeseo's individual star continues to rise.14 Her solo OST work, successful MC tenure, and expanding endorsement portfolio suggest a multifaceted career that extends beyond group activities. When she comes of age in 2026, IVE will become an all-adult group—marking the end of an era for the maknae who debuted at just fourteen, yet the beginning of whatever comes next for an artist who has already exceeded every expectation placed before her.