Yim Pil-sung began directing short films in 1997, with Souvenir as his first. Brushing (1998), about an overweight teenage boy who is left home alone with his senile grandfather, was invited to the Clermont-Ferrand International Short Film Festival. Baby (1999) screened at the Venice Film Festival and Karlovy Vary International Film Festival. Mobile (starring Park Hae-il, Yoon Jin-seo, and Yoon Je-moon) was included in the 2003 omnibus Show Me.
In 2005, he made his feature film debut with Antarctic Journal, a tale of six South Korean explorers on an expedition to reach one of the remotest points in the South Pole, until mysterious deaths begin to occur as the human psyche preys on itself amidst the icy, barren landscape. The big-budget film starred Song Kang-ho and Yoo Ji-tae, and was shot in New Zealand. It won the Best Feature Film award in the Orient Express-Casa Asia section of the 38th Sitges Film Festival.
Yim then played a small supporting role in Bong Joon-ho's monster movie The Host (2006), as a white-collar worker who betrays his college friend. He had agreed to appear in the film in exchange for Bong co-writing the screenplay to Antarctic Journal.
With his second directorial feature, Yim established himself as a genre filmmaker whose works explore the depths of horror and fantasy. Inspired by the titular fairy tale, in Hansel and Gretel (2007) a young man (Chun Jung-myung) gets lost in a forest and stumbles into a house inhabited by three strange children (Shim Eun-kyung, Eun Ji-won and Jin Ji-hee) who refuse to let him leave. It received a Special Mention at the 12th Puchon International Fantastic Film Festival in 2008 and won two awards at the 29th Fantasporto in 2009, the Special Jury Prize in the Fantasy competition and Best Film in the Orient Express sidebar.
Despite praise for their striking visuals and surprising narrative twists, both of Yim's films were unsuccessful at the box office, which led to him having difficulty finding financing for his succeeding projects.
In 2007, Yim and Kim Jee-woon (as co-directors) began filming the sci-fi omnibus Doomsday Book. But financing problems halted production; it resumed in 2010, and the film was released in 2012. Yim wrote and directed two of the film's three segments. Both black comedies, the first segment A Brave New World is about a zombie invasion caused by contaminated meat (starring Ryoo Seung-bum), while the third segment Happy Birthday is about a family hiding in an underground shelter as an 8-Ball-shaped asteroid wipes out mankind (starring Jin Ji-hee). Doomsday Book won the top prize at the 16th Fantasia Festival, the Cheval Noir Award for Best Film.
Yim had next planned to direct a suspense drama about a married American expat who falls for a Korean femme fatale. Titled Flower of Evil, it entered pre-production in 2009 but was eventually shelved. Weekend Prince, a comedy about three men in their thirties who get roaring drunk one weekend (which had Park Hae-il and Song Sae-byeok attached), similarly did not come to fruition.
In 2010, twelve Korean directors and cinematographers shot short films using the iPhone 4 for the iPhone 4 Film Festival (later renamed the Olleh Smartphone Film Festival). Yim's short Super Nerds: No Pain No Gain is a comedy about two die-hard iPhone fans and their journey to find someone who can attach a protective film to their newly purchased iPhones without causing air bubbles to form (in the Korean title Super Deokhu, "deokhu" originates from the Japanese word "otaku").
Yim then starred in two mockumentary-style films in 2013. In E J-yong's Behind the Camera, an absentee filmmaker attempts to direct a film remotely via Skype. Then in Bong Man-dae's comedy Playboy Bong, Yim played a director shooting an erotic-horror film in Bali who gets replaced when the film's producer is disappointed in the sex scenes.
Seven years after Hansel and Gretel, Yim returned with his third feature in 2014. Scarlet Innocence is a modern-day retelling of the classic Korean folktale Simcheongga; in the original, a virtuous girl named Shim Chung sacrifices herself so that her father's sight may be restored. But in Yim's film noir, a university professor gradually succumbing to blindness moves to a rural town and begins an obsessive affair with a young woman 17 years his junior (played by Jung Woo-sung and Esom, respectively). Scarlet Innocence made its world premiere at the 2014 Toronto International Film Festival.A Bit Bitter (short film, 1996) - planner
Souvenir (short film, 1997) - director, screenwriter
Brushing (short film, 1998) - director, screenwriter, editor, producer
Baby (short film, 1999) - director, screenwriter, producer
No Blood No Tears (2002) - extra
Mobile (short film, 2003) - director, screenwriter
Antarctic Journal (2005) - director, screenwriter
The Host (2006) - actor
Hansel and Gretel (2007) - director, screenwriter
A Night on Earth (short film, 2010) - actor
Super Nerds: No Pain No Gain (short film, 2010) - director, screenwriter
Doomsday Book (2012) - director, screenwriter
Waiting for Jang Joon-hwan (short film, 2012) - cameo
Behind the Camera (2013) - cameo
Playboy Bong (2013) - actor
Scarlet Innocence (2014) - director, screenwriter