As she built her filmography in the following years, Park overcame early criticism of her acting skills and eventually gained respect as an actress in TV series such as Bitter Sweet Life, Coffee House and The Innocent Man, as well as the films The Fox Family, A Love, and The Scent.

Her profile photos were eventually handed over to a Chinese agency, and several auditions later, this led to Park making her acting debut in China.

Using the stage name Park Si-yeon, she appeared in small roles in three CCTV dramas, and also landed an advertising contract with cosmetics company Enprani.

In 2005, Park made her acting debut in her native country of South Korea with the SBS TV drama My Girl, for which she received unanimously bad reviews.

[4] But Park continued to work, appearing in more dramas and making her film debut in the 2006 quirky comedy-horror-musical The Fox Family; gradually her acting showed marked improvement.

[5] She became known for playing women who drove men to their destruction and misfortune: In the gangster film A Love, the lover of Park's character goes to prison after defending her,[6] in the MBC drama Bitter Sweet Life, she was a gold-digging mistress with a lonely soul,[7] in spy film parody Dachimawa Lee, she was a sexy agent, and in the KBS drama The Slingshot, she sacrifices herself and becomes the enemy's possession in exchange for her boyfriend's freedom.

"[11][12] Describing Park as "extremely kind," director Pyo Min-soo said he incorporated her real-life personality in writing her character: a bright, cheerful, and caring career woman who at the same time is hardworking, frank and confident.

"[19][20][21][22] She then starred in the melodrama The Innocent Man, playing a woman who betrays her lover to serve her own ambition and puts him on the path to destructive revenge.

[23][24][25] Critics have credited Park's mature performance, saying she mastered the character's complicated nature in a way that heightened the tension of the story, and was not overshadowed by leading actors Song Joong-ki and Moon Chae-won.

[26] After giving birth and being indicted for propofol use in 2013, Park returned to television with the 2014 cable drama The Greatest Marriage, in which her character struggles to balance single motherhood and a successful career as an anchorwoman.

[27][28][29] In 2015, she made her Hollywood debut in Last Knights, an action film set in medieval times about a band of warriors who seek revenge on a corrupt emperor.

[34] Park first became known to the Korean public not through her acting roles, but as the girlfriend of popular singer-actor Eric Mun (from K-pop boy band Shinhwa), whom she began dating in 2004.