He went on to establish himself with starring roles in the television dramas Dream High (2011), Moon Embracing the Sun (2012), as well as in the top-grossing films The Thieves (2012) and Secretly, Greatly (2013).

His performance as King Lee Hwon in Moon Embracing the Sun won him the Baeksang Arts Award for Best Actor – Television.

[10] His first major acting was in a stage play of Shakespeare's comedy A Midsummer Night's Dream delivering the role of Puck.

[12] By 2006, Kim completed elementary, middle and high school in Gangnam, Seoul and debuted as a TV actor in 2007 after auditions.

[15] Based on a true story, it tackles the serious issues of school cheating, competitive academic standards, and interactive blogging in a fresh way.

[17] For the latter half of the year, Kim appeared in the food-based variety show Delicious Quiz (also known as The Taste of Life) as one of the hosts[18] and in the short film Cherry Blossom.

[22] Kim raised his profile through memorable turns as the younger version of the male lead characters in Will It Snow for Christmas?

[27] As the only young actor in a cast of idols, Kim studied song and dance for three months at JYP Entertainment to pull off the required scenes in the drama.

[30] Kim's popularity skyrocketed when he starred in the hit period drama Moon Embracing the Sun as the King Leehwon.

[37] Beating out heavyweight veterans such as Han Suk-kyu, Shin Ha-kyun and Cha Seung-won, Kim said "I am very grateful for this moment, but I am ashamed as well.

[38] Kim made his big-screen debut in the star-studded heist film The Thieves, touted by the press as the Korean version of Ocean's Eleven.

[40] In 2013, Kim was cast to play the role of a North Korean spy who infiltrated South Korea as a village idiot in the movie Secretly, Greatly, an adaptation of the popular webtoon series Covertness by Hun.

[45] It became massively popular across Asia, especially in China; it had over 14.5 billion hits as of February 2014 on the online video platform iQIYI and also sparked trends in fashion, make-up and restaurants.

[57] Kim's wax figure made in his image was displayed at Madame Tussauds, Hong Kong[58] and Musée Grévin, Seoul in 2015.

[62] The film tanked at the box office and received negative reviews from the critics for its direction, storyline, characters' information; saying that only Kim saved the movie with his acting to some extent.

[66] Kim made headlines in news when he returned to his acting career through his special appearances on dramas Hotel del Luna and Crash Landing on You.

[74] S. Poorvaja of The Hindu said of Kim's acting that he brought "Gang-tae alive on screen perfectly — someone whose silent world weariness slowly but steadily progressed to sparkling eyes, smiles and enthusiasm.

[76] In 2021, Kim starred in Coupang Play's television series One Ordinary Day, based on the British television series Criminal Justice, played the role of Kim Hyun-soo, a normal college student whose life turns upside down when he unexpectedly becomes the key suspect of the murder case.

[77] On December 21, 2021, Gold Medalist announced that it will produce and promote actor Kim Soo-hyun's digital human together with EVR Studio.

That has an appearance like a real person and can use facial expressions and plans to be used in a variety of industries including entertainment, metaverse, movies, and advertising in the future.

Along with actor Jang Dong-gun, Korean opera singer Ahn Sook-sun and people from 45 nations, they delivered the message of "One Asia" at the second part of the highlight stage.

[97] In April 2014, during his tour of Asia, Kim donated about ₩200 million to the China Children & Teenager's Fund from a Gucci charity event.

[100] In January 2017, Kim along with 32 top stars of South Korea joined an online fund raising event, Give Love, to help NGOs dedicated to protecting children's rights.

[107][108] In 2014, Kim Soo-hyun appeared in an ad alongside Gianna Jun for Chinese bottled water company Hengda bingquan.

[125] In late November 2017, Kim's agency announced that he had completed his five weeks of basic training, placing fourth as an outstanding trainee.