In November 1995, a cable television station was looking to recruit and hire new actors; Won Bin applied and was accepted in his last semester of high school. He started to take acting classes at the station's headquarters and appeared in several dramas. The following month, Won Bin signed an acting contract with a talent agency.
Won Bin made his screen debut with a supporting role in the 1997 drama film Propose. His role in Ready Go! (1998) helped hone his acting chops. After Ready Go!, he took a break and entered a college called Paekche Institute of the Arts in 1998 to take acting classes. In 1999, Won Bin came back to the screen with a lead role in drama Kwangki from which he was recognized as a promising young actor and a teen heartthrob.
He made his big breakthrough in 2000 with drama Tough Guy's Love (Kkokji) and Autumn in My Heart. His role as a rebellious youngest son in Kkokji proved his acting potential and his role in the widely successful drama landed him on the A-list for Korean performers. Autumn in My Heart gained wide popularity in Asia and he became one of the most popular Korean actors in Korea and Asia as well. In 2002, Won Bin was involved in the first South Korea and Japan joint production drama Friends.
Won Bin also had roles in a number of popular films, including Guns & Talks and My Brother, but it is his portrayal of the sensitive younger brother in the blockbuster war film Taegukgi (2004) that cemented his international fame. With the success of the critically acclaimed Taegukgi, recognition of his acting skills has reached an ever-wider international audience. Taegukgi was the best selling film in South Korea in 2004 with 11.75 million admissions.
His career was interrupted by his mandatory Service to the South Korean Army. After graduating from the Graduate School of Arts in Yong-In University in 2005, Won Bin started his military duty in November 2005 and stationed at the Korean Demilitarized Zone, a position for which he volunteered. On June 2, 2006, the military officially confirmed that Won Bin would be no longer active. The decision was made by the military when Won Bin sustained injury to his ACL. He had undergone surgery and was officially discharged on June 7, 2006. After the surgery, he had gone through rehabilitation program for more than one year to recover from the injury.
Won Bin was appointed as UNICEF Goodwill Ambassador of the Korean Committee on September 6, 2007. He has participated in various programs and charity events in Korea for UNICEF from that time on, and has appeared in several promotional videos.
In April 2008, Won Bin confirmed that his next film would be Mother directed by Bong Joon-ho. Filming started in September 2008 and finished in February 2009. The film was selected to compete in the Un Certain Regard section of the 2009 Cannes Film Festival. This was followed by the 2010 film The Man from Nowhere, his final film appearance to date.
He was mentioned in the lyrics of Ladies' Code's single Kiss Kiss, composed by Super Changddai. The lyrics said, "난 오늘밤 꿈에서 난 원빈 오빠가 나타나 줄 텐데" (Tonight, in my dreams, Won Bin oppa will appear). His character in The Man from Nowhere was referenced by Krystal Jung in the 2013 drama, The Heirs. In the 2015 Korean drama Kill Me, Heal Me, the character of Park Seo-joon, Oh Ri-on, told Secretary Ahn that the elusive Writer Omega's looks were rumored to be "on the Won Bin level".
In July 2013, news broke that Won Bin and Actress Lee Na-young were in a relationship. The two came to known each other when Lee joined the same agency as Won Bin in August 2011. The pair started dating a year later in August 2012. Won Bin married Lee on May 30, 2015 in a small, private ceremony in Won's hometown Jeongseon, Gangwon Province. A press release from their agency Eden 9 in August 2015 announced that the couple were expecting their first child.