Eun Hye had her first major acting role in popular Korean drama, Princess Hours (also known as "Goong"). Initially, fans of the Goong manhwa had questioned her acting ability, which lead to controversy. The drama began with average ratings, but as it continued, viewership increased to 28.3% nationally, leading to an extension of the first season (from 20 to 24 episodes) and a Princess Hours special on MBC. Although Yoon and the other main actors were invited to work on a second season of Princess Hours, only one of them officially agreed to do so. Another director of a different company eventually filmed a spin-off series with brand new characters, known as Goong S which was not to be confused with the actual Goong sequel planned by the original director and company.
Due to the success of her first drama, Yoon has continued acting in other dramas such as The Vineyard Man. Like most Korean dramas at that time, The Vineyard Man initially suffered from low ratings due to strong competition from the MBC 45th anniversary drama Jumong; however, the drama surprised everyone as ratings increased and reached a 15.6% on its finale.
Yoon's second lead role was for MBC's Monday/Tuesday drama The 1st Shop of Coffee Prince that began to air in July 2007, where she plays the employee Go Eun-chan at a coffee shop, who was once a master of Taekwondo. With her short haircut and tomboyish ways, she is presumed to be a boy by the owner of the shop, thus leading to romantic complications. The 1st Shop of Coffee Prince garnered higher ratings than her first series Princess Hours. Coffee Prince reached the viewership ratings as high as 32.1% in Seoul, making it number one for its timeslot and 29.9% nationwide. During the time of her popularity peaking, Yoon was also diagnosed with pernicious anemia.[6